Abraham Trembley's Approach to Research on the Organism ...

AMER. ZOOL., 29:1105-1117 (1989)

Challenge to the Specialist: Abraham Trembley's Approach toResearch on the Organism—1744 and Today1

HOWARD M. LENHOFF2 AND SYLVIA G. LENHOFF

Department of Developmental and Cell Biology, University of California,Irvine, California 92717

SYNOPSIS. We define an organismic biologist as one whose research is focused primarilyon a single organism, or group of related organisms, and who investigates virtually thewhole of nature as lived by that organism. We contrast an organismic biologist with aproblem-oriented biologist, that is one who uses an organism, or a group of organisms,in order to investigate a particular question. In our view, the consummate organismicbiologist has an outlook that allows her or him to conduct research on organisms with anopen eye, to follow the cues offered by the organism, and to switch and learn new disciplineswhen the challenge to understanding the particular organism leads the investigator inthose directions. We provide examples of the organismic approach of Abraham Trembleyworking in the eighteenth century and of the senior author working in the twentiethcentury. Both focused their investigations mostly on the freshwater hydra. While studyinghydra, Trembley demonstrated that: (a) complete animals can regenerate from small, cutpieces of those animals; (b) animals can reproduce asexually by budding; (c) tissue sectionsfrom two different animals of the same species can be grafted to each other; (d) thematerials oozing out of the edges of cut tissue have properties that fit the definition ofprotoplasm as described by Dujardin one hundred years later; (e) living tissues can bestained, and those stained tissues can be used in experiments; and (f) "eyeless" animalscan exhibit a behavioral response to light. Some of the topics investigated in hydra by thesenior author and his students are: (a) behavioral responses to the peptide reduced glu-tathione and to tryosine; (b) mechanism of activation of the receptor to glutathione;(c) migration of nematocytes; (d) algal-animal endosymbiosis; (e) an unusual disulfide-linkedcollagen of nematocyst capsules; (f) components and action of nematocyst venom;(g) intracellular digestion of radioactive protein; (h) composition of and role in cellularadhesion of the mesoglea; and, (k) a developmental mutant and role of nerve cells inpromoting budding. We conclude with a proposal for one way to train future organismicbiologists at the graduate and post graduate levels. This proposal grew out of our per-ception of the need to provide environments that nurture scientists who, by studyingorganisms, will find and define new experimental systems for the next waves of biologicaldiscovery yet to come when the specialists begin to investigate even more intensively theinteractions between cells, tissues, organisms, and communities. Specifically, we proposethat on the campuses of several major universities having a broad range of graduateprograms, there be established year-round Institutes for Organismic Marine Biology focusedon the investigation of organisms not previously amenable to systematic experimentation.We believe that if America's biology is to remain vibrant and innovative, organismicbiology should be an integral component in any long term planning for research andtraining in the biological sciences.

INTRODUCTION in both the eighteenth and twentieth cen-We divide this paper into three parts: t u r i e s - examples that may have a particular

(1) An introduction to the organismic message to the aspiring biologists of theapproach to the study of the freshwater twenty-first century. (3) The presentationhydra as practiced by Abraham Trembley o f a specific proposal for one way to fosterin the eighteenth century. (2) The provi- the training of those practitioners of thesion of various examples of the organismic "new organismic biology."approach to the study of hydra as practiced l f e e l Jt necessary to preface these

remarks by stating that I am not a trainedzoologist. My graduate training was in

1 From the Symposium on Is the Organism Necessary? enzymology and I Still work in that field,presented at the annual meeting of the American During these sessions, the analogy of theSociety of Zoologists, 27-30 December 1987, at New P , . j uOrleans, Louisiana. organism as a machine was used a number

* Delivered by H. M. Lenhoff. When the first per- of times. The way that I was trained inson singular is used, it refers to the senior author. biochemistry to study how a machine works

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1106 H. M. LENHOFF AND S. G. LENHOFF

was to toss a hand grenade into one, pickup a few of the pieces that look alike, andanalyze them. Thus, in view of my back-ground in enzymology, you should find itunderstandable why in some ways I studythe functioning of the animal as would areductionist.

On the other hand, through the influ-ence of my postdoctoral mentor, the lateW. F. Loomis, and some very talentedgraduate and postgraduate students, I havecome to appreciate the organism, one inparticular, and have over the years gainedan organismic outlook. So please keep thediverse nature of my experience in mindas I present my views on the study of theorganism.

How do we define "organismic biology"?

We define an organismic biologist as onewhose research is focused primarily on asingle organism, or group of related organ-isms, and who investigates virtually thewhole of nature as lived by that organism.We contrast an organismic biologist witha problem-oriented biologist, that is onewho uses an organism, or a group of organ-isms, in order to investigate a particularquestion.

Once an organismic biologist starts toconduct research on an animal, that biol-ogist may be led to investigate one phe-nomenon after another with no immedi-ately apparent connection between themand without regard to the discipline of biol-ogy in which he or she is trained or evento the problem initially under investiga-tion. That is, at one point the subjectbeing studied may be behavior; at anoth-er instance, developmental biology; atanother, physiology; at still another, ecol-ogy; and then maybe back to behavior, oragain to physiology. Or, as Trembley (seeLenhoff and Lenhoff, 1986) wrote in hispreface, "I was swept along, as it were, fromone observation to another with barely thetime to make notes in my journal."

In our view, the consummate organismicbiologist has an outlook that allows her orhim to conduct research on organisms withan open eye, to follow the cues offered bythe organism, and to switch and learn new

disciplines when the challenge of theunderstanding of the particular organismleads the investigator in those directions.

How does one become a productiveorganismic biologist today? We believe thatit is necessary to wed the sophisticatedexpertise of the problem- or discipline-based orientation with an outlook whichencompasses the broad and deep study ofthe whole organism. In the last part of thistalk I will suggest a way to train such organ-ismic biologists.

ORGANISMIC APPROACH OFABRAHAM TREMBLEY

Abraham Trembley (1710-1784) ofGeneva was to become a major figure inthe burgeoning of experimental zoology inEurope during the Enlightenment. He didnot start out in the field in which he wasto make his mark, however. While a stu-dent at the Calvin Institute the youngTrembley did his thesis on the calculus(Baker, 1952). Seeking employment aftercompleting his studies, he went to Hollandwhere he became the tutor of the two chil-dren (Fig. 1) of a Dutch nobleman, CountWilliam Bentinck, on an estate in theHague. There, while introducing the chil-dren to the aquatic life present in theditches around the estate, Trembley foundfreshwater hydra (Fig. 2), small animalsthat, unknown to Trembley at first, hadbeen described by Leeuwenhoek in 1704.Intrigued by the puzzling characteristics ofthis strange creature, Trembley deter-mined to study it carefully, and in a fewshort years he made one remarkable dis-covery after another with the "polyp witharms shaped like horns," as he called it (seeBaker, 1952).

Among Trembley's many findings pub-lished in his beautiful Memoires (Trembley,1744; Lenhoff and Lenhoff, 1986 [Englishtranslation]) are the demonstrations, usinghydra, that: (a) complete animals canregenerate from small, cut pieces of thoseanimals; (b) animals can reproduce asexu-ally by budding; (c) tissue sections from twodifferent animals of the same species canbe grafted to each other; (d) the materialsoozing out of the edges of cut tissue have

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ORGANISMIC BIOLOGY: A CHALLENGE 1107

FIG. 1. Vignette showing Trembley in his study at the mansion of Count Bentinck in Holland. He is turninga hydra inside out as his two pupils watch. The vignette precedes Trembley's fourth Memoir (1744).

properties that fit the definition of proto-plasm as described by Dujardin onehundred years later; (e) living tissues canbe stained, and those stained tissues can beused in experiments; and (f) "eyeless" ani-mals can exhibit a behavioral response tolight.

In his Memories Trembley describes anadditional 50 or more discoveries (see Len-hoff and Lenhoff, 1985) in the fields ofnatural history, taxonomy, morphology,developmental biology, behavior, physiol-ogy, and ecology of hydra. He also reportson his work on other organisms anddescribes new methods and techniques,with a scientific philosophy remarkablymodern for its time.

As we were preparing a list of Trem-bley's contributions in the chronologicalorder in which they were discovered, wenoticed that he was following an "organ-ismic chain" of observations which led himto remarkable and lasting discoveries thathad no apparent connection to the initialobservations that started the chain (Fig. 3).We will describe just three parts of Trem-bley's chain of successive observations,

those leading to the discovery of photo-taxis, regeneration, and grafting.

PhototaxisTrembley began his researches on hydra

by observing the animal and its behaviorboth in nature and in his study under con-ditions that simulated the conditions foundin nature. As Trembley aptly commented(see Lenhoff and Lenhoff, 1986):

In order to come to know an animal, itis very useful to observe it in its naturalconditions, that is in the midst of every-thing that surrounds it in the placeswhere it is found. For this reason it isdesirable that the vessel in which the ani-mal is kept be arranged very much likeits original habitat. This expedient canhasten considerably the research one ispracticing. It can even lead to findings whichotherwise would not be made. (Italics added)

While examining the waters that he col-lected from the ditches in Holland, Trem-bley initially paid attention to the "livelycreatures" there rather than to the seem-ingly immobile green hydra attached to the

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FIG. 2. Drawings by P. Lyonet of a hydra and of various views of parts of the tentacles. From Plate 5 ofTrembley's Memoires.

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ORGANISMIC BIOLOGY: A CHALLENGE

Observing hydras collected from nature

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Showing tentacles are hollow. Noticing their contractionsand demonstrating a connecting iopening between parent and bud I

TObserving their propensity toward light4•Observing hydras eating

Noticing that hydras havecolored granules after eating

Sectioning hydras and discovering regeneration

\

Discovering budding in Slylaria

Examining granules emanating from cut pieces of hydrasDiscovering the viscous materialholding these granules together

» Discovering budding in hydras as aform of asexual reproduction

Discovering Lophoput. andbudding in it

Showing that nutrient substances entered thegranules and vesicles in the lining of the gut alongwith the colored material of the ingested food

Inverting the hydra to see if granules of the outerpart of the body wall would play a role inassimilation while they were on the "inside"

Accidentally observing grafting of bud toparent hydra

Inititating series' of grafting experiment*

Fie. 3. Organismic chain of Trembley's experiments and observations. (From LenhofF and LenhofF, 1986)

side of his jar. Then one day he saw thehydras contract and extend. After observ-ing them for several more days, he sawthem take steps. Convinced they were ani-mals, he paid them little heed for a monthor so until by chance he noted that theywere attracted to light. Through some

clever controlled experiments he then pro-ceeded to demonstrate for the first timethat eyeless animals, in this case, hydra,move toward light, a behavior now char-acterized as positive phototaxis. In onestudy, for example, he covered a jar ofhydra with a cardboard sleeve in which a

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small opening had been cut. He thenrotated the sleeve at intervals and trackedthe migration of the specimens, which wasalways toward the light coming in throughthe opening (see Bodemer, 1967).

Regeneration

The experiments on phototaxis excitedTrembley into observing hydra systemat-ically. He began to note that individualhydra varied in their number of tentacles,or "arms," a variation that is a decidedlyodd characteristic for an animal. Hethought of bisecting some hydra to checkagain the vague possibility that they mightbe plants, although he seriously doubtedit.

This idea led him to devise a series ofelegant experiments which demonstratedto an astonished world that whole animalscan regenerate from small pieces of thatanimal. He began by bisecting a hydratransversely and examined both parts fre-quently. Within a day he saw the excisedposterior half grow tentacles and laterdevelop into a whole hydra. He then pro-ceeded to carry out virtually every con-ceivable variation of experiment on regen-eration to confirm his initial observation.

As with his discovery of phototaxis,Trembley again notes that his discovery ofthe ability of hydra to regenerate was ser-endipitous (see Lenhoff and Lenhoff,1986):

Because of its nature, that finding [i.e.,regeneration] was to be not the fruit oflong patience and great wisdom, but agift of chance. It is to such a happy chancethat I owe this discovery which I made,not only without forethought, but with-out my ever having had in my entire lifeany idea even slightly related to it.

GraftingWhile Trembley was investigating

regeneration, he noticed that whenever hecut a hydra, many "granules" oozed out ofthe cut part of its body wall into the sur-rounding solution. For a while Trembleyexplored the role of those granules inspreading nutrients through the body. Atone point he wondered if he could provide

nutrients to the hydra through the gran-ules by turning the animals inside out. Thenthe granules of the inner skin would be onthe outside of the animal and thus closerto the nutrients which he would add to thesolution surrounding the inverted hydra.

It was a complication of turning the hydrainside out that led Trembley to observe hisfirst graft (Lenhoff and Lenhoff, 1984). Inone instance he saw that the tip of an imma-ture bud which was not inside the invertedparent had poked through a hole in theskin of the mother and "seemed com-pletely united to it" at the new site. Thisfinding led him to devise a series of care-fully designed experiments proving con-clusively that pieces from two differenthydras of the same species could be graftedtogether and that grafts between hydras ofdifferent species would be rejected.

A recapitulation

In all these instances Abraham Trem-bley's organismic study of hydra led to thediscovery of fundamental phenomenadescribed for the first time in any organ-ism. Then, like today's discipline-orientedbiologists, he tried to understand thosephenomena through experiments using thetools of the day. To explain his findings,he would search for more facts. Or as hewrote (see Lenhoff and Lenhoff, 1986):

Thus we cannot do better to explain thefacts we know than by trying to discovernew ones. Nature must be explained bynature and not by our own views.

AN ORGANISMIC APPROACH PRACTICEDIN THE TWENTIETH CENTURY

Before telling you of the organismicapproach that I have been practicing forabout 25 years, I should state that when Iwas first invited to participate in this sym-posium, it was because of my own work onhydra, not because of our research on thecontributions of Abraham Trembley. Butthere seem to be some provocative analo-gies.

For example, my mentor, the late W. F.Loomis, and I started out working on anestate in Greenwich, Connecticut, farremoved from any institutions of higher

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learning. And like Trembley, we startedour work with hydras that we collectedfrom a pond on that estate. But we wereluckier than Trembley in that we had morepowerful tools to help us understand thephenomena that we literally chanced uponwhile trying to "tame" hydra for modernlaboratory research. I will highlight thebranched organismic chain of discoverythat led to some of our more importantfindings.

Culture of hydra en masse

I was fortunate to apprentice under W.F. Loomis during the pioneering years ofthe modern renaissance of research onhydra. Our initial goal was to develop a"simple" multicellular animal into a labo-ratory model for the study of cellular inter-actions, especially those taking place dur-ing normal and abnormal development.Loomis picked hydra and developed a wayto grow hydra in the laboratory (Loomis,1954). Later we designed a way to growhydra in mass cultures (Loomis and Len-hoff, 1956; Lenhoff and Brown, 1970).After all, we were both trained as biochem-ists, and needed large numbers of animalsinto which "to toss our hand grenades"before isolating enzymes and other factors.While getting to know hydra, Loomis madetwo important observations: (1) the feed-ing behavior of hydra was controlled inpart by the reduced tripeptide glutathione(Loomis, 1955) and (2) an increase in thepartial pressure of carbon dioxide stimu-lated specimens of Hydra littoralis to dif-ferentiate gonads (Loomis, 1957).

Migration MC-labeled nematocytes

After leaving the Loomis Laboratory, Iused those two observations as leads withwhich to continue my investigations on thebiology of hydra. For example, since CO2affected the development of hydra, I startedto administer radioactive CO2 to the ani-mal. In one instance I found that the gaswas incorporated into Krebs cycle inter-mediates, glutamic and aspartic acids, andinto proteins of interstitial cells of hydra,cells considered to be multipotent. I alsoused these findings to follow by radioau-tography the migration of nematocytes

(cells making the nematocysts) from thebody tube of the hydra into the animal'stentacles (Lenhoff, 1959).

Algal-hydra endosynnbiosis

After I became familiar with the tech-niques for incorporating labeled CO2 intohydra, I thought of using 14CO2 to labelthe algae in the symbiotic green hydra andto study the pathways of the products ofphotosynthesis (Lenhoff and Zimmer-mann, 1959). This preliminary study wasnoticed by Leonard Muscatine, then agraduate student at the University of Cal-ifornia at Berkeley (and the current pres-ident of the American Society of Zoolo-gists). Subsequently a series of collaborativestudies (Muscatine and Lenhoff, 1963,1965a, b) triggered a wave of research onthe biochemistry and physiology of endo-symbiosis led mostly by Muscatine and hisstudents.

Chemistry of nematocyst capsule

Oddly enough, my research on thechemistry of nematocysts got its start whenI was showing some colleagues how to usea sonic oscillator to break up animal tissue.For my demonstration I used a leftoverbatch of 20,000 hydra. As the homogenateof the disintegrated hydra started to settleout, I noticed that very quickly a layer ofa whitish sediment settled to the bottom ofthe tube. Microscopical analysis showed thewashed sediment to be a relatively cleanpreparation of the four nematocyst typesof hydra, most of which were discharged.We analyzed an acid hydrolysate of the dis-charged capsules and found them to be richin hydroxyproline, proline, and glycine, anindication that a major component of thesestructures was a collagen-like protein (Len-hoff et al., 1957). Up until that time col-lagens were not thought to be commonoutside of the vertebrates. Previously, thenematocyst capsules had been presumed tobe composed of a chitinous material (seeHyman, 1940). Because nematocysts werethought to be formed in the body tube, tomigrate to the tentacles for use, and thento be lost after they were discharged, weused a measure of the presence of hydroxy-proline in the different regions of the body

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of hydra as a chemical marker for themigration of the nematocytes, each con-taining a hydroxyproline-rich nematocyst,to the tentacles (Lenhoff and Bovaird,1961).

Intracellular digestion of protein

While I was learning how to handle14CO2, some 35S-labeled mouse tissue wasmade available to me. After dipping smallpieces of this labeled tissue in reduced glu-tathione and feeding it to hydra, I carriedout a biochemical study of how protein (95S-labeled) is digested in hydra. The resultsof this study confirmed and extended thecytological evidence showing that most ofthe ingested food is taken up by the gastriccells of the endoderm, stored in food vac-uoles, and eventually completely digestedthere (Lenhoff, 1961a).

Composition and role of mesoglea

During the course of the digestion study,I needed to separate the ectodermal fromthe endodermal epithelial layers. BarbaraBarzansky and I subsequently used a mod-ification of this separation technique to iso-late the matrix lying in between those twocell layers, the mesoglea. Our analysis ofthe isolated mesoglea showed it to bechemically very similar to the basementlamina associated with vertebrate epithelia(Barzansky and Lenhoff, 1974). We canconjecture that cnidarians such as hydradeveloped an effective substance as a basalaffiliate of epithelial cells, and that subtleevolutionary alterations may have led tothe basal lamina associated with vertebrateepithelia. Continuing our studies of themesoglea of hydra, we (Day and Lenhoff,1981) studied the specificity of the adhe-sion of epithelial cells from hydra and othertissues to isolated preparations of hydramesoglea.

On the mechanism of activation of thereceptor to reduced glutathione

A strange organismic chain of observa-tions and discoveries led to our detailedstudy of the mechanism by which reducedglutathione (GSH) activates receptors forthat molecule in hydra. Having the purepreparation of mostly discharged nema-

tocysts referred to earlier, we decided touse a series of stains in order to comparethe characteristics of the undischargednematocysts with those of the relatively fewundischarged nematocysts in those prep-arations. We found that undischargednematocysts showed a material staining forcalcium inside the capsule whereas thatmaterial was absent in discharged capsules(Johnson and Lenhoff, 1958). We hypoth-esized that calcium ions may play some rolein the mechanism by which nematocystsdischarge, a hypothesis now gaining cur-rency (see, for example Mariscal, 1988).Based upon this observation we started totest the discharge of nematocysts in solu-tions having various concentrations of cal-cium ions and noted that the ion had to bepresent in the environment for the nema-tocysts to discharge in vivo.

Simultaneously, we thought that we hadbetter check to see if calcium ions were alsorequired for reduced glutathione to acti-vate the hydra's feeding response, and sureenough they were. Before publishing ourresults, we thought it necessary to developa quantitative in vivo assay for the feedingresponse activated by GSH, and did so(Lenhoff and Bovaird, 1959). Only afterrefining this assay (Lenhoff, 19616) couldwe proceed to define the pH profile of thereceptor to GSH (Lenhoff, 1969), and thestructure-function relationships of the tri-peptide as it bound to the receptor (seeLenhoff, 1981 for review). We like to pointout that all of these physico-chemicalparameters were determined as we exper-imented on intact living animals.

A developmental mutant

Unexpectedly, our research on the feed-ing response led to our discovery of astrange developmental mutant of hydra,one of the first ever described (Lenhoff,1965). It happened this way. We wantedto study the mechanism of the activationof the receptor by GSH in an axenic envi-ronment. To do this we reasoned that weshould get from hydra fertilized eggs, eachencased in a capsule, sterilize the capsules,allow newly developed hydra to emergefrom the capsules into a germ-free envi-ronment, and grow clones of axenic ani-

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mals. After collecting over 100 encap-sulated zygotes, however, we lacked thetime to sterilize them and thus allowed theembryos to hatch. About one third of thosethat emerged were not normal either intheir morphology or developmental prop-erties. As luck would have it, among themwas one which was particularly interestingin that it would eat and grow, but wouldnot bud. Using this mutant, we were ableto prepare heterocytes, i.e., organisms ofthe same species, but composed of differingnumbers of cells of a slightly differinggenotype (Filosa, 1962). Subsequent workusing these heterocytes demonstrated a rolethat nerve cells can play in controlling thebudding process of hydra (Novak and Len-hoff, 1981).

Control of one behavioral response bytwo different chemoreceptors

An organismic chain of observations andexperiments not only branches, but alsocan loop. For example, while controllingthe amount of food given to the just-men-tioned heterocytes, we noticed a strangeconstriction occurring around the "neck"of hydra when it was given a second meala few hours after it had received its firstone. An analysis of the stomach contentsof the hydra and further experimentsshowed that the formation of this constric-tion, a process that we called the neckresponse, appeared to be a mechanismwhereby the hydra could retain foodalready ingested while trying to ingestmore. The response was triggered by thepresence of the amino acid tyrosine in thedigestive cavity of hydra and the simulta-neous presence of GSH, released by thenewly captured prey, on the outside of thehydra. This finding was the first demon-stration of two different molecules con-trolling a physiological response in a cni-darian (Blanquet and Lenhoff, 1968).

Disulfide bonds hold proteins of thenematocyst capsule together

Another loop of the organismic chaincan be illustrated through two exciting dis-coveries by students who came to my lab-oratory to study nematocysts. One of them,Richard Blanquet, convinced me that his

system for studying nematocysts, i.e., theacontia of sea anemones, might prove moreuseful for getting pure preparations of onetype of nematocyst in either the undis-charged or discharged state. Thus, afterdeveloping a method for growing the seaanemone Aiptasis pallida in the laboratory,we purified large preparations of undis-charged nematocysts, made them dis-charge, and analyzed the capsules. Weshowed that these capsules, like those fromhydra, had a major collagen component;but, in addition, we showed that those col-lagens were held together by disulfidebonds (Blanquet and Lenhoff, 1966). Thisfinding was not expected because at thetime collagens were thought to contain few,if any, sulfur amino acids.

Components of nematocyst venom

While harvesting the large preparationsof undischarged nematocysts, we weresimultaneously stockpiling significantamounts of the discharged contents of thosenematocysts. That stockpile proved to bethe starting material for an elegant studyinitiated by David Hessinger, who subse-quently elucidated for the first time activecomponents of the venom of nematocysts,i.e., a neurotoxin and a phospholipase A(see for example, Hessinger et al., 1973;Hessinger and Lenhoff, 1976).

Some reflections

This organismic chain of research I havedescribed shows the combined influencesof my mentors. From the late Nathan O.Kaplan, an enzymologist and my Ph.D,advisor, I learned the importance ofsearching for more and more facts "toexplain the facts we know." From the lateW. F. Loomis, my first postdoctoral men-tor, I learned how to work with organismsand how to treat them with the same pre-cision that I had learned from Kaplan touse with simpler systems. And from thestaff of the former Biophysics Division ofthe Department of Terrestrial Magnetismof the Carnegie Institution of Washington,I learned of the importance of devising newtechniques that would allow the livingorganism to reveal its secrets. As I pursuedresearch on organisms on my own, I felt

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that the overall message these mentors gaveme was best expressed by Ernest Baldwinof Cambridge University who wrote in1950:

The knowledge of the chemist and theoutlook of the biologist must be lawfullyand properly wedded; they must inhabitthe same house in harmony and mutualunderstanding if the union is to be fruit-ful

I do not presume to speak for other organ-ismic biologists. The examples I have pre-sented show that I use the term "organ-ismic research" to describe a way ofdiscovery, and "discipline-based research"a way of explanation.

I personally believe that today's biolo-gists are better prepared to investigate theorganism in the holistic sense if they aretrained in at least one experimental disci-pline, such as biochemistry. It is one thingto acquire the skill to use a particular bio-chemical technique, and it is quite anotherto approach the study of an organism as abiochemist would investigate a simpler sys-tem. To put it another way, experimentalbiology that is based heavily upon a foun-dation in the physical sciences brings a wayof thinking to the study of organisms, notsimply physical and chemical techniques.As Baldwin said, a proper wedding of thesetwo approaches will give a better under-standing of the organism. To return to theintroductory section of this paper and toAbraham Trembley, we believe that hisearlier training in the calculus, the subjectof his thesis at the Calvin Institute, influ-enced his precise and systematic approachto the study of hydra.

The organism has many secrets to tell.As Dr. Russert-Kraemer (1989) said in thediscussion following her talk, and in herown inimitable way, "we have to pretendthat we are inside of the organism and learnits language to get at its secrets." Perhapsthe path to those secrets winds throughdisciplines outside our own particular areasof graduate and postdoctoral training.

My approach has been to use my trainingas an enzymologist "to get into the mind"of hydra. There are those who might saythat my approach works only with simpler

animals, such as hydra. I would agree inpart to that comment because the per-ceived simplicity of hydra was the featurethat initially attracted W. F. Loomis andme to investigate that freshwater cnidar-ian. But 30 years of experience has taughtme that hydra is not as simple as Loomisand I had previously imagined, and thatsome of the cells of hydra take on manymore functions than do cells of the morecomplex animals. Furthermore, I believethat as we expand our knowledge of themore complex animals, invertebrate andvertebrate, and learn to control both theirexternal and internal fluid environments,then the same organismic approach toinvestigation which Loomis and I were ableto use with hydra will also be productivewith those more complex creatures.

A PROPOSAL FOR TRAINING THEORGANISMIC BIOLOGISTS OF THE

TWENTY-FIRST CENTURY

To conclude, how shall we train theorganismic biologists of the 21 st century?We start from the premise that we are nowin a great era of specialized biologicalresearch, but that there are risks for thefuture in producing a biology of extremespecialization. It appears that today thereare more and more biological scientistsfocusing on fewer and fewer problems.

We see the need to provide environ-ments that nuture scientists who, by study-ing organisms, will find and define theexperimental systems for the next waves ofbiological discovery yet to come when thespecialists begin to investigate even moreintensively the interactions between cells,tissues, organisms, and communities.

Institute of Organismic Marine Biology

As one means of providing such an envi-ronment, we propose that on the campusesof several major universities having a broadrange of graduate programs, there beestablished year-round Institutes forOrganismic Marine Biology focused on theinvestigation of organisms not previouslyamenable to systematic experimentation.The purpose of these institutes would beto train organismic biologists of the kindwe have defined (Lenhoff, 1987).

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These institutes should provide the intel-lectual and physical environment that willallow research on marine organisms to becarried out 12 months of the year. Theyshould attract a critical number of sym-pathetic faculty who are prepared to enternew disciplines when opportunities arise.

Although there are many excellentmarine stations today, none constitute thekind of institute we propose. Their limi-tations seem to stem from both geographicand intellectual isolation. Geographically,most marine institutes are too far fromyear-round academic institutions. They arefine for summer programs, but there is lit-tle time to carry on sustained and system-atic interactive research. In addition, as arule isolated institutes can not justify theexpensive equipment and large libraryholdings that researchers need today.Because most are located in remote coastalvillages, they lack the community ameni-ties that potential resident faculty requirefor their families.

In addition to geographic isolation, therecan also be intellectual isolation. Histori-cally, this has taken the form of a barrierbetween the resident biologists, who mayharbor some distrust for those trained inthe more molecular and experimental dis-ciplines. Molecular biologists, on the otherhand, may be perceived as exhibiting var-ing degrees of arrogance toward their moreclassically trained colleagues.

Graduate trainingGraduate students who wish to study with

the Institute faculty should enroll, beforethey begin their research, in a graduateprogram in the University that will givethem thorough training in a single "hard-core" discipline, such as biochemistry,molecular biology, cell biology, immunol-ogy, or neurobiology. The Institute wouldteach them how to apply their specialtytowards investigating organismic prob-lems.

Postdoctoral training

The Institute should also offer specialtraining programs through which recentM.D.s and Ph.D.s in such fields as molec-ular biology, biochemistry, or physiology/

biophysics, study and conduct researchunder the tutelage of the Institute's morebiologically trained faculty who will showthese young scientists how to bring theirexpertise to the study of an organism. Like-wise, in an equally symbiotic fashion, brightyoung Ph.D. graduates who have special-ized in some aspects of such classical fieldsas invertebrate zoology, marine biology, orecology should profit immensely fromstudying and interacting with faculty andfellow students trained in the more exper-imental laboratory disciplines.

These newly trained organismic biolo-gists will find that the ocean, like space forthe physicist, offers a vast territory toexplore. It hosts a multitude of organismsliving under extremes of living conditions,organisms which because of their unusual,little studied and little understood adap-tations, have "devised" unique ways to sur-vive. Those organisms may provide keys tosolving some of the most complex prob-lems in biology.

As Dr. Barnes described in his presen-tation (Barnes, 1989), there are probablymillions of species yet to be discovered—and each with its own unique adaptations.Some of the known and as-yet-to-be dis-covered species may allow us to answerquestions that we are unable to investigateusing current conventional systems. Stillother species to be tapped may allow us toinvestigate significant biological phenom-ena that we have never even thought ofexamining before.

Organismic biologists of the future willfind that research on whole organisms pro-vides more opportunities for serendipity,those great discoveries of chance, than doesresearch on a more refined system, such asa purified protein.

In conclusion, we believe that if Amer-ica's biology is to remain vibrant and inno-vative, organismic biology should be anintegral component in any long term plan-ning for research and training in the bio-logical sciences. We are not too sanguinethat the institutes we propose will be estab-lished very soon. Eventually yes, but prob-ably not in the next 10 years.

Thus, in the interim, for you youngerbiologists, if you are to remember one les-

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son from Abraham Trembley, let it be: Donot become a victim of overspecialization.Get a good background in experimentaltechniques and approaches to research,start to observe and investigate yourorganism, and let it, not your preconceivedideas, be your guide.

ADDENDUM

Our views regarding the establishmentof experimental marine stations on cam-puses of major universities grew out of ourown experiences. But as our colleaguespointed out in and after the discussion ofthis paper at the symposium, our basic pro-posal could also apply to the study of otherthan marine organisms. The importantpoint that we wish to emphasize, however,is that a means for keeping those organismsalive and well in a "near natural" habitatmust be established on a campus of a majoruniversity that is close to all of the amen-ities it offers for long term research. Analternative, but much more costly, sugges-tion would be to establish field stations ina variety of locales, fully outfitted with lab-oratories, a wide range of equipment, sup-plies, shops, libraries, and living facilitiesfor a critical mass of faculty and students.Finally, we note that our proposal does notapply to much research in field ecology,which by definition, requires that it be car-ried out in a natural environment, usuallydistant from a major university.

ACKNOWLEDGMENTS

We thank Louise Russert-Kraemer andWalter J. Bock for their constructive andvaluable criticisms.

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