James W. Atz

Effects of methyl testosterone on the testes of a hypophysectomized cyprinodont fish, Fundulus heteroclitus ☆

Administration of methyl testosterone to hypophysectomized, sexually regressed, male Fundulus heteroclitus (2 μg/gm, thrice weekly) initiated the development of nuptial coloration within two weeks. Stimulation of spermatogenesis was evident after 4 weeks, and at 8 weeks free spermatozoa were present in the efferent ducts of 4 out of 6 fish. Although the gonadosomatic index was significantly increased, testis size was one-tenth that of intact males in the breeding season. Eight-week treatment also caused hypertrophy of the epithelium of the efferent ducts and restored the atrophied interstitial cells to near normal breeding condition. A lower dose of methyl testosterone (0.2 μg/gm) for 8 weeks caused essentially similar changes in the testes, but the development of nuptial coloration (attributed to direct action of the androgen) proceeded more slowly.

Viviparity and the maternal-embryonic relationship in the coelacanth Latimeria chalumnae

Embryos of Latimeria chalumnae develop in well-vascularized compartments in the uterine region of the right oviduct. Compartments conform to the shape of their embryos and yolksacs; they represent a stable, gestation-induced oviductal modification. Late-term pups possess large, flaccid, vascular yolksacs almost devoid of yolk. The sac is in close contact with, but does not adhere to, the lumenal uterine surface. A massive vascular plexus occurs in the wall of the compartment at the site of contact with the yolksac ; together they constitute a non-adherent, transposable placenta. The exterior surface of the yolksac is bounded by an attenuated, single-layered, squamous epithelium that surrounds an intercommunicating bed of cortical sinuses. The cortex of the sac is composed mostly of connective tissue stroma. The inner surface is bounded by a layer of yolk-digesting merocytes. Residual yolk occurs as yolk platelets that include yolk crystals. The interior surface of the sac is invested by an uniquely specialized vitelline circulation; no connection seems to exist between the interior of the yolksac and gut. The uterine wall consists of : (1) a lumenal surface composed of an anastomosing network of capillaries with a layer of attenuated, very thin, squamous epithelium, (2) a well-vascularized connective tissue stroma, (3) alternating transverse and longitudinal layers of smooth muscle, also well-vascularized, and (4) an external epithelial layer. Comparison of egg dry weight (184 g) with the estimated dry weights of a late-term pup (171 to 239 g) and a neonate (200 to 280 g) reveals a weight change of − 7 to + 30% and + 9 to + 52%, respectively. This is indicative of matrotrophy. In one female specimen, 19 remarkably large ovulated eggs were found and in another about 30 somewhat smaller ovarian ones. These are many more than ever could be accommodated in the uterine space. During the early and middle phases of development, embryos must be lecithotrophic, using their yolk reserves, with oophagy of fragmented supernumerary eggs as the most probable source of additional nutrients. The well-developed embryonic gut contains brown, amorphous yolk-like material. The limited amount of metachromatic secretory product of the uterine glands can play little or no role in embryonic nutrition.

THE EFFECTS OF LOW TEMPERATURE, AND CORTISOL, ON TESTICULAR REGRESSION IN THE HYPOPHYSECTOMIZED CYPRINODONT FISH, FUNDULUS HETEROCLITUS

1. Low temperature retarded the rate of sexual regression in hypophysectomized male Fundulus heteroclitus.2. Transfer to warm temperature accelerated the rate of post-spermatogonial regression, and the partially regressed interstitial tissue became inactive.3. In contrast, the return to warm temperature stimulated the rate of spermatogonial mitosis. It is suggested that temperature has a direct action on spermatogonial multiplication.4. Cortisol, at a physiological dose, had no significant effect on the condition of the testes.

In Appreciation of Klaus D. Kallman

To be exactly the right person in the right place at the right time does not often happen. When being the right person means having the potential to become one of the world’s greatest fish geneticists, the probability of this happening drops close to zero. However, hindsight makes even minuscule possibilities look good. Adjunct Professor Myron Gordon of the Graduate School of Arts and Science of New York University certainly did not have such prescience when, in 1953, he first met Klaus D. Kallman, a new graduate student looking for a sponsor to direct his doctoral studies. Kallman had led a serious life. He was born in Berlin in 1928 and grew up there throughout the war and into the Russian occupation. He and his family eventually emigrated to the United States, where he continued his education at Queens College and received his B.S. degree in 1952. He had developed a keen interest in genetics as a teenager in Germany and had heard about Dr. Gordon’s laboratory. When he saw the different platyfishes and swordtails attractively disporting themselves, he gladly accepted Gordon’s offer to sponsor him. In less than a year, using a strain of platyfish Gordon had inbred for 16 generations of brother-to-sister matings, making them as genetically alike as identical twins, Kallman was able to begin his pioneering experiments on the immune system of fish. In 1955 he was awarded his M.S. degree and in 1959 his Ph.D. Dr. Kallman also received an honorary Ph.D. from the University of Hamburg in 1992. Kallman’s experiments indicated that a fish’s immune system accepts or rejects transplanted tissue in a way similar to that of the well-known mammalian model, the laboratory mouse. It was up to him to develop a transplantation technique that worked with small fish. Each experimental animal had to be treated in precisely the same way to avoid uncontrolled variations. Moreover, Kallman was planning to make thousands of transplants; therefore, he practiced transplanting fins and other organs from one small fish to another until it took him less than 1 minute to complete each operation. For more than a decade after publishing his doctoral thesis, Kallman used his hard-won technique to demonstrate the existence of individual parthenogenetic fish, to study selffertilizing and gynogenetic species, to utilize the latter in experiments with organ transplants, and to analyze the genetic structure of natural fish populations (Kallman, 1970). Kallman had met his first major scientific problem and had satisfactorily mastered it. Meanwhile, Kallman was becoming familiar with the complex operations of Gordon’s meticulous genetics laboratory, particularly the record system of 3-by-5 cards that tracked the complete pedigree of each fish along with its color pattern, birth, matings, and the final disposition of its body. Furthermore, more than 600 aquaria had to be accounted for, each duly labeled with its inhabitants. Genetic experiments usually involve several generations spanning Received January 31, 2001; accepted March 30, 2001. *Corresponding author: telephone 512-245-0358; fax 512-245-1922; e-mail sk13@swt.edu Mar. Biotechnol. 3, S3–S5, 2001 DOI: 10.1007/s10126-001-0021-6

Fish imagery in art 82: Jonah and the fish

The Prophet Jonah’s story, as told in the Bible and the Koran, has been illustrated many times, especially his being swallowed by a whale,a fish or some mythical sea monster. Inasmuch as the historical texts themselves do not agree as to the taxon involved and provide nodescriptive information except that the creature was marine and of large size, zoologists, cryptozoologists, and art historians seem to havebeen limited to commenting on possible sources of various renditions.This painting is slightly less than 48cm wide and is an Islamic miniature. It was painted in Persia ca. 1400. It is one of many paintingsmade by unnamed artists to illustrate some copies of Jami‘ al-Tawarikh(or ‘World History’), a classic work that includes episodes fromthe Bible, Koran, and life of Buddha. A translation of the texts on Jonah’s arms reads: ‘The disk of the sun entered into darkness’ on hisleft arm and ‘Jonah entered the mouth of the fish’ on his right; the former, which was taken from the Gulistan

The Lure of Latimeria

Weinberg, S. 1999. A fish caught in time. The search for the coelacanth. Fourth Estate, London. 239 pp. £13.99 (also in 2000, idem, HarperCollins Publishers, New York. 220 pp. US

Coelacanth Conservation Council

24.00).

Osmoregulation in Elasmobranchs

Winston Churchill once called a backbencher, who remained silent for nearly twenty years in the British House of Lords and then got up to make a great speech, ‘that coelacanth of a man’. Since then the coelacanth has become a metanym for someone or something that rises up from the past with a great message to tell. True to form, the Coelacanth Conservation Council (CCC) newsletter has performed the same phoenix-like transformation; after being moribund for five years, while the editor was employed at a busy commercial aquarium in Cape Town, the newsletter has responded with alacrity to the discovery of coelacanths in Indonesia and will resume its services to coelacanthophiles worldwide.Since the last newsletter was published in December 1993, the world has changed dramatically, especially with respect to information technology. Information on the coelacanth (and every other imaginable topic) is now readily available on the internet; the fun of establishing the first coelacanth internet site (http://www.dinofish.com) is described by Jerry Hamlin in this newsletter. We nevertheless thought that the CCC newsletter provides a unique, hardcopy service by updating the official coelacanth inventory and bibliography and by publishing interesting accounts of recent developments in coelacanth research and conservation. So we are resuming regular publication, thanks to ‘raja laut’. In the future, the sequence of coelacanth specimens in the inventory of specimens will not be strictly chronological as information is often received on specimens long after they were caught; we nevertheless consider it worth recording all the specimens that come to our attention, in the order that they are reported to us.