Stomach contents of Latimeria chalumnae and further notes on its feeding habits

Synopsis Stomach contents of three Latimeria chalumnae dissected in Japan support the hypothesis that the coelacanth is a predominantly nocturnal bottom or near-bottom drift feeder. Prey items identified in this study (Ilyophis brunneus, Cephaloscyllium sufflans and Beryx decadactylus) and those reported previously are mostly benthic or epibenthic dwellers. The drifting of the coelacanth in a headstanding posture would account for the easy capture of prey that moves within or just above the bottom strata at night.     

The ecology and conservation of the coelacanth Latimeria chalumnae

Synopsis Studies on the ecology of the living coelacanth, Latimeria chalumnae, are reviewed and assessed. Early predictions on the life history of the coelacanth have proved to be accurate but recent findings have improved our understanding of its habitat and feeding preferences, diel activity patterns and social behaviour. A history of coelacanth conservation reveals that there has been a sustained concern for the survival of this species which has eventually culminated in several effective conservation actions in recent years. The coelacanth is threatened by a number of socio-economic and biological factors, but international action directed at managing the fishery in the Comoros should ensure that the species survives. Recent observations on living coelacanths in their natural environment have greatly improved our knowledge of the behaviour and relative abundance of adults. Important priorities for future research include studies on the distribution and abundance of juveniles and breeding adults, both off the Comoros and elsewhere. The coelacanth is a highly specialised, precocial fish which occupies a unique place in biology. Co-ordinated international efforts should continue to be made to understand and conserve this remarkable fish.     

Bibliography of the living coelacanth Latimeria chalumnae,with comments on publication trends

Synopsis A list of published references on the coelacanth Latimeria chalumnae is provided. All known publications in the scientific literature are included as well as popular articles and press reports that are considered to provide new information or interpretations. Marked trends are noticeable in the literature as different disciplines have been applied to research on the coelacanth over the past five decades. The bibliography lists a total of 823 publications including 490 papers in journals, 37 books, 3 theses, 45 chapters in books, 166 popular articles, 22 reports and 60 newspaper articles. Studies on taxonomy and morphology initially dominated the literature followed by reports on research in the fields of physiology, behaviour, breeding biology, ecology and conservation as frozen and eventually live specimens became available for study. The literature on the living coelacanth is predominantly in English, French, Japanese and German but references in 12 other languages were also traced. The dominant authors in the first decades of coelacanth research were the French scientists J. Millot and J. Anthony and the South African describer of the first and second coelacanths, J.L.B. Smith. In subsequent years French, British, American, South African, Japanese, Canadian and German authors, among others, have made significant contributions.     

Computed tomography and magnetic resonance imaging studies of Latimeria chalumnae

Synopsis Recent radiologic imaging techniques (CT[Computed Tomography] and MRI[Magnetic Resonance Imaging]) were used to investigate the cranial anatomy of the coelacanth Latimeria chalumnae. The non-invasive CT and MRI techniques were performed successfully on a 1.45 m female specimen. This specimen had been frozen a year earlier for future research; the CT was conducted on the frozen animal, whereas the MRI method was performed immediately after thawing. The CT technique provides information about differential density of the organism (especially informative with respect to hard tissues, bone and cartilage), whereas three different types of MRI (proton resonance T₁, T₂ and flash) distinguish cartilage, muscles, and different connective tissues. A total of 381 CT cross sections (2 mm thick with 1 mm of overlap) through the head region were used in a computerized three-dimensional reconstruction program to address questions concerning cranial morphology. The results obtained from these radiologic imaging techniques confirmed most of the basic anatomy known from traditional dissections. However, the morphology of complex structures. such as the cartilaginous processes of the neurocranium, and the integration of the branchial arches and palate can only now be described more accurately.     

Habitat and population size of the coelacanth Latimeria chalumnae at Grand Comoro

Synopsis In 1987 and 1989 coelacanths were observed for the first time in their natural habitat with the help of submersibles. Coelacanths were found between 150–253 m depth, their preferential depth seems to be around 200 m; the water temperature ranged between 16.5–22.8° C. During the day coelacanths aggregate in small non-aggressive groups in sheltered lava-caves. Caves might be a limiting factor for distribution. At night they leave the caves for hunting by drifting singly along the steep lava slopes. They migrate between different caves located within a large home range covering more than 8 km coastline. Coelacanths are site-attached, some for a period of at least 2 years. Our own observations and earlier catch records show that only the west coast of Grand Comoro is a suitable coelacanth habitat with more structural complexity and prey fish abundance than other coastlines of the island. From our survey we estimated a total coelacanth population off Grand Comoro to be 150–210 individuals; a saturated population would be 370–510 individuals. This small relict population seems to be stable. International protection of coelacanths against commercial interests is needed     

Probable evolution of the coelacanth's reproductive style: lecithotrophy and orally feeding embryos in cichlid fishes and in Latimeria chalumnae

Synopsis The living coelacanth is a livebearer. Yolk seems to be the main source of nutrients and of oxygen to the embryo (fetus). Long before birth, young may also possibly feed orally on histotrophe secretion and egg debris. This type of reproduction evolved, as in most other fishes, from oviparity. The Carboniferous coelacanth Rhabdoderma exiguum had eggs of much lesser yolk volume and may represent an earlier form of oviparity with hiding, guarding or brooding type of parental care. The Jurassic coelacanth Holophagus (Undina) and the Cretaceous Axelrodichthys appear to have already evolved the internal-bearing style. Much of this evolutionary sequence is similar to that in cichlids. Ancestral cichlids are substrate tenders and nesters, with small eggs, little yolk and a feeding larva with indirect development. Mouthbrooding cichlids evolved a few, large eggs with denser yolk, direct development and, ultimately, orally feeding embryos while yolk is still in ample supply. Mixed feeding from yolk and orally ingested food in cichlids and in coelacanths is shown to be an enhanced mode of food delivery to the embryos over that from each source separately, in order to produce directly a better developed or larger young at the time of release, i.e. independence. Increase in egg size is regarded as an environmentally induced, altered pattern of yolk synthesis and an initial component of the epigenetic mechanism leading towards greater specialization. Carotenoids are incorporated within the yolk to assist the oxidative metabolism of the developing embryo.     

The hemoglobin of the crossopterygian fish, Latimeria chalumnae (Smith). Subunit structure and oxygen equilibria

There are five oxidation-reduction states of horseradish peroxidase which are interconvertible. These states are ferrous, ferric, Compound II (ferryl), Compound I (primary compound of peroxidase and H₂O₂), and Compound III (oxy-ferrous). The presence of heme-linked ionization groups was confirmed in the ferrous enzyme by spectrophotometric and pH stat titration experiments. The values of pK were 5.87 for isoenzyme A and 7.17 for isoenzymes (B + C). The proton was released when the ferrous enzyme was oxidized to the ferric enzyme while the uptake of the proton occurred when the ferrous enzyme reacted with oxygen to form Compound III. The results could be explained by assuming that the heme-linked ionization group is in the vicinity of the sixth ligand and forms a stable hydrogen bond with the ligand.The measurements of uptake and release of protons in various reactions also yielded the following stoichiometries: Ferric peroxidase + H₂O₂ → Compound I, Compound I + e^? + H⁺ → Compound II, Compound II + e^? + H⁺ → ferric peroxidase, Compound II + H₂O₂ → Compound III, Compound III + 3e^? + 3H⁺ → ferric peroxidase.Based on the above stoichiometries and assuming the interaction between the sixth ligand and heme-linked ionization group of the protein, it was possible to picture simple models showing structural relations between five oxidation-reduction states of peroxidase. Tentative formulae are as follows: [Pr·Po·Fe-(II) $\text{\$}\text{?}$PrH⁺·Po·Fe(II)] is for the ferrous enzyme, Pr·Po·Fe(III)OH₂ for the ferric one, Pr·Po·Fe(IV)OH^? for Compound II, Pr(OH^?)·Po⁺·Fe(IV)OH^? for Compound I, and PrH⁺·Po·Fe(III)O₂^? for Compound III, in which Pr stands for protein and Po for porphyrin. And by Fe(IV)OH^?, for instance, is meant that OH^? is coordinated at the sixth position of the heme iron and the formal oxidation state of the iron is four.     

An inventory of all known specimens of the coelacanth Latimeria chalumnae,with comments on trends in the catches

Synopsis A list is presented of all known specimens of the coelacanth Latimeria chalumnae based on a survey of the literature and of museum, aquarium and university holdings. Details are given of the date, place, time and depth of capture, the name and age of the fisherman, the length, weight and sex of the fish, the first literature record, the method of preservation and the present location of specimens, if known. A new number is assigned to each specimen. At least 172 coelacanths are known to have been caught since 1938. The first coelacanth was caught off South Africa but all properly documented, subsequent specimens have been caught off the islands of Grand Comoro and Anjouan in the Comoros. An appeal is made to the Comoran authorities for each specimen that is caught to be made available for scientific study. Museum authorities are also encouraged to allow their specimens to be X-rayed or dissected so that vital information can be obtained on fecundity, foetal nutrition and dietary preferences. It is essential for the coelacanth conservation effort that this inventory is maintained by the Coelacanth Conservation Council.     

Bile salts of the lungfishes Lepidosiren, Neoceratodus and Protopterus and those of the coelacanth Latimeria chalumnae Smith.

1. Bile salts of the coelacanth Latimeria chalumnae Smith (five specimens) and of the three living genera of lungfish (Dipnoi) were examined as completely as possible and compared. 2. The small 'bile acid' fractions include no more than traces of well-known C27 or C24 acids (free or conjugated) and the functioning bile salts must be regarded as alcohol sulphates. 3. Comparison of the alcohols suggest that (a) Latimeria stands biochemically outside the animal group which includes the Dipnoi, (b) Protopterus and Lepidosiren are more closely related to one another than either is to Neoceratodus, (c) all four primitive osteiychtheans have some amphibian affinities, (d) there are affinities between Latimeria and Dipnoi and ostariophysan families (especially Cyprinidae and Catostomidae) and (e) there are biochemical links between Dipnoi and lampreys.     

The international program of research on Latimeria in the 1960s

Synopsis The international phase of coelacanth research, meaning substantial activity and involvement by people from countries other than the Comoros, France and South Africa, began in 1961. In that year UNESCO initiated detailed planning for a multinational, multiyear investigation of many aspects of the physical, chemical and biological environments of the Indian Ocean that was called the International Indian Ocean Expedition (IIOE). In response to a request for proposals for the United States' program in biology in the IIOE the author, early in 1961, initiated a plan for what became a 3-month long expedition by 15 scientists from three countries on board the R/V TE VEGA. In 1964 the expedition went to northern Madagascar and the Comoro Islands. Efforts to capture and study at least one specimen of Latimeria were a major component of the activities. This paper describes important aspects of the preparations leading up to this expedition and the events that occurred during the expedition, in the context of the search for the coelacanth. The expedition did not capture a fish itself, but arrangements made during the trip resulted in a specimen (CCC no. 37), partly fixed in formalin and then frozen, being sent to the author in early 1965. A detailed study of the fats and oils contained in this fish resulted in a prediction concerning the probable neutral buoyancy of Latimeria that has been supported by the recent behavioral observations from submersibles. The paper concludes with a brief account of the activities of the Committee on Latimeria that was sponsored by the U.S. National Academy of Sciences from 1968–1972.     

矛尾鱼Hoxa—11基因克隆及5′端序列分析

Hoxa-11基因调节鱼类鳍和四足动物肢的发育,在脊椎动物进化过程中起着重要的作用,利用人和鼠的Hoxa-11基因保守序列设计了两个兼并引物,通过PCR扩增到了矛尾鱼的Hoxa-11基因,经克隆和DNA序列分析,该片段为2065bp,包括绝大部分外显子Ⅰ,内含子和部分外显子Ⅱ,编码204个氨基酸,其氨基酸序列与人、鼠、鸡、蛙和斑马鱼的同源性分别为66.0%、67.6%、74.4%、72.8%和59.7%。外显子Ⅰ的长度从矛尾鱼到蛙、鸡、鼠和人呈现逐步上升趋势,人比矛尾鱼增长了16%,进一步分析,外显子Ⅰ可分为4个区域;两个高度保守区域,1个中度保守区域和1个可变区域,外显子Ⅰ的长度变化主要是由于可变区域内丙氨酸同聚物以及两侧富含甘氨酸和丝氨酸序列的累积。矛尾鱼只有1个由两个丙氨酸组成的同类物,蛙有1个由5个连续丙氨酸组成的同聚物,而鸡、鼠和人有3个丙氨酸同聚物,其中最大的同聚物由7个连续丙氨酸组成,而且在同聚物两侧出现了富含甘氨酸和丝氨酸序列。这表明可变区域可能与脊椎动物进化和鳍-肢转换过程中新功能的获得有关。同源异型盒所在的外显子Ⅱ区和剪接位点是高度保守的。内含子的长度变化较大,但在其内部也发现了两个高度保守的35bp和16bp的DNA片段,这两个片段在人、鼠、鸡、蛙和矛尾鱼中是完全相同的,这些序列的高度保守性提示其功能上的重要性。     

Purification and characterization of pepsinogens from the gastric mucosa of African coelacanth, Latimeria chalumnae, and properties of the major pepsins

Two major pepsinogens, PG1 and PG2, and one minor pepsinogen, PG3, were purified from the gastric mucosa of African coelacanth, Latimeria chalumnae (Actinistia). PG1 and PG2 were much less acidic than PG3. Their molecular masses were estimated by SDS-PAGE to be 37.0, 37.0 and 39.3 kD, respectively. When incubated at pH 2.0, PG1 and PG2 were converted autocatalytically to the mature pepsins through an intermediate form, whereas PG3 was converted to an intermediate form, but not to the mature pepsin autocatalytically. The N-terminal sequencing indicated that the 42 residue sequences of the propeptides of PG1 and PG2 were essentially identical with each other, but different from that of PG3. A phylogenetic tree based on the N-terminal propeptide sequences indicates that PG1 and PG2 belong to the pepsinogen A group, and PG3 to the pepsinogen C group. From the phylogenetic comparison, coelacanth PG1 and PG2 appear to be evolutionally closer to tetrapod pepsinogens A than ray-finned fish pepsinogens A, consistent with the traditional systematics. Pepsins 1 and 2 were essentially identical with each other and rather similar to mammalian pepsins A in the pH optimum toward hemoglobin (pH 2-2.5), the cleavage specificity toward oxidized insulin B chain and strong inhibition by pepstatin, except that they possessed a significant level of activity in the higher pH range unlike mammalian pepsins A.     

不同品种、日龄和饲养方式对肉鸡肠道菌群的影响

目的研究品种、日龄和饲养方式对肉鸡肠道菌群的影响。方法选择北京油鸡和AA肉鸡各120只,分笼养和地面平养两种饲养方式,每种饲养方式60只鸡(5个重复,每个重复12只),于7、14、21和42日龄无菌收集十二指肠、回肠和盲肠内容物,分析各肠段肠道菌群变化。结果 (1)从十二指肠、回肠到盲肠微生物种类越来越丰富,相同肠段不同处理间随日龄的增加微生物种类也不断增加,十二指肠、回肠主要菌是植物乳酸杆菌和双歧杆菌,盲肠主要菌是拟杆菌和梭菌,且AA肉鸡拟杆菌数量大于北京油鸡;(2)品种对十二指肠和回肠条带数影响不显著,但北京油鸡大于AA肉鸡,日龄对回肠条带数的影响显著。品种与日龄的互作对盲肠的影响显著,品种、日龄和饲养方式三个处理的互作对回肠条带数的影响显著。(3)十二指肠各处理间肠道菌群的相似性在42日龄达到稳定,回肠在21日龄稳定,盲肠从7日龄到42日龄各处理间肠道菌群相似性变化不大。结论不同肠段的微生物区系有明显差异,品种、日龄和饲养方式对肉鸡肠道微生物区系有不同影响,但微生物区系会随着肉鸡日龄的增加趋于稳定。     

Effect of temperature,photoperiod, and feeding on the rate of tail regeneration in a semiaquatic plethodontid salamander

Salamander tail autotomy improves survival, but loss of the tail can subsequently be costly. For example, burst swimming speed is significantly slower after autotomy in desmognathan salamanders, which may increase predation risk in aquatic habitats. However, any long-term cost of tail loss is contingent on the rate of tail regeneration. To examine variation among seasons and environments in the cost of tail autotomy, we tested the effect of temperature, photoperiod, and feeding on tail-length re-growth in the semiaquatic plethodontid salamander Desmognathus conanti. Eight experimental groups (n=15 each, equivalent in body size) were tested. After acclimation for four weeks at one of two temperatures (either 10 °C or 20 °C) and one of two photoperiods (either L:D 9.5:14.5 h or 14.5:9.5 h), 60% of the tail length was autotomized for each individual. After autotomy, each experimental group was maintained under unique conditions of temperature (either 10 °C or 20 °C), photoperiod (either L:D 9.5:14.5 h or 14.5:9.5 h), and feeding (either fasting or weekly feeding). The length of the regenerated tail portion for each individual was measured each week until the group with the fastest re-growth had regenerated 50% of the lost tail length. Low temperature had a large, negative effect, fasting had a small, negative effect, but photoperiod had no significant effect on tail re-growth. The large thermal effect resulted from a combination of delayed initiation of tail-length re-growth and reduced regeneration rate thereafter at low temperature. We conclude that the cost of salamander tail autotomy differs among seasons and environments based on variation in temperature and food availability.     

Feeding strategy and locomotion of Cambrian hyolithides

The Chengjiang (Cambrian Stage 3) and Balang (Cambrian Stage 4) Konservat-Lagerstätten of South China have produced abundant hyolithide hyoliths; however, little attention has been paid to their feeding strategy and the role it played in the ecosystem. Hyolithides preserved in coprolites from the Chengjiang Biota and associated with a Tuzoia carcass from the Balang Fauna reveal the fluid feces consuming and scavenging strategies of this group. Size distribution of hyolithides demonstrates that their dietary habit is ontogenetically dependent, with juveniles having ingested organic-rich material whereas adult food consumption was more likely by a variety of species-dependent methods The first discovery of hyolithides in association with locomotion traces and burrows indicates they were not only epibenthic vagrants, but also shallow horizontal burrowers. The new discoveries reported herein enhance our understanding of the feeding strategy and other behaviours of Cambrian hyolithides.     

Mating effects on the feeding and locomotion of the German cockroach, Blattella germanica

Abstract. Feeding cycles and daily locomotory patterns of the German cockroach, Blattella germanica L. (Dictyoptera: Blattellidae), were correlated with the ovarian development cycle. To meet the nutrient requirement for ovarian development, females increased feeding before forming oothecae. Locomotory activity also increased when females became sexually receptive. All these activities reached a peak just before the formation of oothecae. Ovarian development ceased and locomotion and food consumption decreased during pregnancy. Both mated and virgin females showed similar reproductive cycles, but those of mated females were more precisely timed (intervals between successive oothecae, and pregnancy duration, were 5 ± 0.6 and 17 ± 0.6 days, respectively). However, the intervals between successive oothecae of virgin females were longer and less synchronized. During this longer interval, feeding took place immediately following the discharge of the ootheca, but locomotory activity increased 5 days later when females became sexually receptive. Mated females increased locomotory activities 1 or 2 days before the end of pregnancy, presumably searching for deposition sites for oothecae. Female adults were found to exhibit a daily nocturnal locomotory pattern. However, under the physiological demands of reproduction, the pattern could be changed, for example by increasing activity during photophase when females were sexually receptive. The physiological effects of reproduction override the control of the daily locomotory pattern by its diel clock.     

Gene Structure and Amino Acid Sequence of Latimeria chalumnae (Coelacanth) Myelin DM20: Phylogenetic Relation of the Fish

The structure of Latimeria chalumnae (coelacanth) proteolipid protein/DM20 gene excluding exon 1 was determined, and the amino acid sequence of Latimeria DM20 corresponding to exons 2–7 was deduced. The nucleotide sequence of exon 3 suggests that only DM20 isoform is expressed in Latimeria. The structure of proteolipid protein/DM20 gene is well preserved among human, dog, mouse, and Latimeria. Southern blot analysis indicates that Latimeria DM20 gene is a single-copy gene. When the amino acid sequences of DM20 were compared among various species, Latimeria was more similar to tetrapods than other fishes including lungfish, confirming the previous finding by immunoreactivity (Waehneldt and Malotka 1989 J. Neurochem. 52:1941–1943). However, when phylogenetic trees were constructed from the DM20 sequences, lungfish was clearly the closest to tetrapods. Latimeria was situated outside of lungfish by the maximum likelihood method. The apparent similarity of Latimeria DM20 to tetrapod proteolipid protein/DM20 is explained by the slow amino acid substitution rate of Latimeria DM20.