Early development of the cephalic skeleton of Barbus barbus (Teleostei, Cyprinidae)

The inception, and development of the cephalic skeleton of Barbus barbus from hatching to 24 days passes through periods of fast and slow growth; these rates are not the same in different parts of the skull. Trabeculae, parachordal plates, Meckelian cartilages and hyposymplectics are present at hatching. Then the cartilaginous floor of the neurocranium develops, the pars quadrata, the hyoid bars and branchial arches elements appear shortly before the first movable dermal bones, the dentaries, maxillae and opercles. The first bone of the braincase to appear is the parasphenoid; other bones develop subsequently and at the same time: the angular, quadrate, interopercle and fifth ceratobranchial. Later the splanchnocranium continues to develop at a relatively fast rate while the neurocranium shows little growth. The braincase does not begin to close before the 24th day, nor do the first bones of the skull roof appear, while the bucco-pharyngeal apparatus is complete, having the adult shape. The early constitution of the latter structures seems to be linked with the mechanical demands of biological functions such as breathing and feeding.     

Composition of the seminal Fluid and ultrastructure of the spermatozoon of turbot (Scophthalmus maximus)

Mean values of the composition of the seminal fluid of 30 turbots were: osmotic pressure =306 mosml⁻¹, pH =7–31, total protein =8.8mg ml¹, Na⁺=133.0 mmoll¹, K⁺=3.80mmoll⁻¹, Cl⁻=129mmol l⁻¹. The rounded nucleus, the reduced middle piece and the typical '9 + 2' structure of the flagellum mean that the spermatozoon of turbot can be considered to be of a primitive type.     

Anin vitro,serum-free organ culture technique for the study of development and growth of the dermal skeleton in fish

Summary To develop a serum-free, chemically definedin vitro organ culture system enabling the study of epithelial-mesenchymal interactions in development and growth of fish dermal skeleton, we investigatedin vitro continuation of scale regeneration in the cichlid fishHemichromis bimaculatus. The culture medium in our system is based on Leibovitz medium (L-15) supplemented with vitamin C, additional amino acids and HEPES. With this basis medium, we examined the effects of all trans-retinoic acid, dexamethasone, and prostaglandin-E2 (PG-E2), factors known to exert an effect on development and growth of teeth and bone in mammalian culture systems, on thein vitro regeneration of scales. These effects were compared with those obtained by supplementation of the basis medium with newborn and fetal calf serum. To evaluate our culture system, the medium that allowed to mimick in the best possible way thein vivo regeneration of scales (i.e., the basis medium plus dexamethasone and PG-E2) was also tested on thein vitro development of teeth in the same fish species. Our serum-free, chemically defined organ culture system enablesin vitro development and growth of both scales and teeth. With this model culture system, it is possible to evaluate thein vitro effects of hormones, growth factors, and other substances on growth and development of dermal skeleton in fish.     

Physiological responses to handling in the turbot

Turbot Scophthalmus maximus were cannulated via the afferent branchial artery and were either net-confined in sea water or in air for 9 min to monitor the stress response of a hatchery-reared marine flatfish. No mortality was observed. Aerial exposure appeared to mobilize plasma free fatty acids and stimulate the interrenal tissue but had no effect on circulating glucose or lactate levels. This pattern was qualitatively similar to that induced by net-confinement in sea water, although the magnitude and duration of the changes were more marked in the turbot handled in sea water. Aerial exposure had no effect on plasma osmolality, protein, or Cl⁻ concentrations and only a minor effect on plasma Na⁺ concentrations, which was in sharp contrast to the ionoregulatory disturbance noted in turbot which were net-confined in sea water. However, plasma K⁺ and cortisol concentrations were similarly elevated by both handling procedures. The results from these experiments suggest that whilst similarities with the salmonid physiological stress response are apparent, the lack of a plasma glucose response may represent a fundamental difference in turbot stress physiology.     

Mineralized cartilage in the skeleton of chondrichthyan fishes

The cartilaginous endoskeleton of chondrichthyan fishes (sharks, rays, and chimaeras) exhibits complex arrangements and morphologies of calcified tissues that vary with age, species, feeding behavior, and location in the body. Understanding of the development, evolutionary history and function of these tissue types has been hampered by the lack of a unifying terminology. In order to facilitate reciprocal illumination between disparate fields with convergent interests, we present levels of organization in which crystal orientation/size delimits three calcification types (areolar, globular, and prismatic) that interact in two distinct skeletal types, vertebral and tessellated cartilage. The tessellated skeleton is composed of small blocks (tesserae) of calcified cartilage (both prismatic and globular) overlying a core of unmineralized cartilage, while vertebral cartilage usually contains all three types of calcification.     

Timing of epiphyseal development in the flipper skeleton of the harbour porpoise (Phocoena phocoena) as an indicator of paedomorphosis

Epiphyseal development was investigated on X‐rays of flippers from 158 harbour porpoises from Danish waters. Development followed a proximodistal pattern similar to what is known in other cetacean species. Ossification of epiphyses was rare in the phalanges of the first and fifth digits and in the more distal phalanges of the second, third and fourth digits. Along with the morphology of the first metacarpal and the more distal phalanges this suggested paedomorphosis relative to delphinids. Male and female porpoises showed similar progression of epiphyseal development until approximately the sixth year. From then on, female porpoises showed more progressed development than males. This suggests a higher level of paedomorphosis in the male porpoise. The mechanism behind phocoenid paedomorphosis seems to be progenesis, probably as an adaptation towards a high reproductive rate relative to the delphinids.     

Comparing levels of homoplasy in the primate skeleton

Hard-tissue morphological characters (bones and teeth) are a primary source of information about the evolutionary history of primates. These tissues are commonly found as isolated elements in the fossil record and studied as three separate partitions: the dentition, the cranium, and the postcranium. The relative phylogenetic utility of characters from each partition is often called into question with respect to varying amounts of homoplasy. In this paper, the consistency index (CI) was used to measure levels of homoplasy in each data partition for a sample of fossil and living primates. Sources of bias in the collection and treatment of data and in the internal structure of the data set are addressed. These biases include number of taxa, number of characters, ordering of characters, amounts of polymorphically scored or missing data, and character-state distribution. The results of this study suggest that the levels of homoplasy are very similar, though the postcranial data may be slightly less homoplastic than either the dental or cranial data.     

Visualizing the postembryonic development of Sarcophaga peregrina (flesh fly) by NMR microscopy

The postembryonic development of the flesh fly was studied using high resolution nuclear magnetic resonance imaging. Because this development occurs in a puparium, this process cannot be observed directly using standard histological techniques. The remodelling of histolysing larval tissues to developing imaginal tissues including the yellow body, a transient alimentary structure, and the integration of the developed adult structure were revealed in the images. Most surprisingly it was found that a large gas space that forms in the central region of the prepupa moves to the dorso-anterial region in less than 5 min due to the larval–pupal apolysis together with separation of the developing pupal epidermis from the puparium.     

Morphological changes during metamorphosis in cod (Gadus morhua L.), with particular reference to the development of the stomach and pyloric caeca

Metamorphosis in cod, Gadus morhua L., was investigated with respect to morphological changes in the alimentary tract (mouth, stomach and pyloric caeca) and external characters (finfold and fin development). Morphometric measurements and histological investigations were made on both larvae and juveniles and all fish lengths are given as standard length. Median unpaired fins started to develop when the fish were 9–10 mm in length. The larval median finfold was resorbed when fish reached a size of 11–15 mm. The vertebrae were formed in fish of 11–20 mm. The supraterminal mouth, seen in larvae <12 mm, changed gradually to a sub-terminal position in juveniles larger than 65 mm. The development of the stomach and pyloric caeca started at 15 mm and the juvenile form was seen in fish of 40 mm. The ability to store and grind food particles in the stomach developed gradually as fish increased in size from 20 to 40 mm. Compared to many other teleost species, cod juveniles are relatively large when the stomach and pyloric caeca become fully developed. These findings may have important implications for both start-feeding of cod larvae and the weaning of juveniles on to artificial diets.     

Functional morphology of the caudal skeleton in teleostean fishes

The basic function of the caudal skeleton in teleostean fishes is to support the caudal fin, but its parts contribute to this function in somewhat different ways. The main axis for this support is the upturned terminal end of the vertebral column, which ends at the base of the uppermost principal rays. The uroneural struts just ahead of this axis provide support for it. The parts of the caudal skeleton behind and below this upturned axis, the hypurals and parhypural, not only support the caudal rays but also provide a means for differential movements between the upper and lower parts of the fin base. This basic caudal skeleton varies with the position of the fish in the sequence of teleosten evolution, the way in which the fish uses its caudal fin, and to some extent with the shape of the fin.     

The nature of the skeleton and skeletogenic tissues in the Cnidaria

Calcification of zooxanthellate and non-zooxanthellate corals from 2 classes and 3 orders of Cnidaria was investigated using scanning and transmission electron microscopy and light microscopy. The ultrastructure of the skeleton and skeletogenic tissues (the calicoblastic ectoderm) from areas of active and non-active skeleton deposition were investigated. The results show that the fundamental cellular mechanism of calcification is similar in all 3 orders, and that the role of endosymbiotic zooxanthellae may be one that is concerned with the removal of waste products of the calcification process. The results are discussed with respect to the concepts of calcification and its evolution in the Cnidaria.     

Dietary ascorbic acid requirements during the hatchery production of turbot larvae

The effect of high ascorbic acid (AA) levels transferred through enriched live food was evaluated for turbot Scophthalmus maximus larvae in two consecutive feeding experiments. The same feeding strategy was applied to all treatments, except for the AA content of the live food which was manipulated through bioencapsulation with ascorbyl palmitate. This resulted finally in a low, medium and high-AA treatment. The AA incorporation levels in the turbot larvae (up to 1400 μg AA g DW⁻¹) were correlated with the AA content of the live food administered. However, feeding the high AA concentration resulted in the same values as for the medium treatment, indicating a saturation of the body AA reserves. Under standard culture conditions, no differences in growth nor overall survival could be detected among the different groups, illustrating that the dietary AA requirements of larval turbot are met by non-enriched live food containing already 500 μg AA g DW⁻¹. The larvae of the high-AA treatment, however, showed a better pigmentation rate (47 and 32% for experiments 1 and 2, respectively) compared to the other groups (35 and 25%, respectively). Evaluation of the physiological condition applying a salinity stress test revealed an improvement by feeding extra AA, significantly in the medium-AA treatment. Though not significantly different, cumulative mortalities after challenge with Vibrio anguillarum amounted to 50% for the control v. 40% for the fish fed medium and high-AA diets, respectively. Moreover, the onset of mortalities in this study was slower (not significantly) for the fish fed the extra AA.     

骨骼的内分泌功能

既往认为骨骼是支持机体基本结构和参与运动及钙磷代谢的主要器官。近年发现组成骨骼的成骨细胞和破骨细胞能合成和分泌多种骨调节蛋白、生长因子、脂肪因子、炎症因子和心血管活性肽等多种生物活性物质,以旁/自分泌方式调节骨骼系统功能,并能通过血液循环远距分泌的方式,调节机体能量代谢、炎症反应和内分泌稳态等。     

Allozyme variation in turbot (Psetta maxima) and brill (Scophthalmus rhombus) (Osteichthyes, Pleuronectoformes, Scophthalmidae) throughout their range in Europe

Two species of coastal flatfish (brill and turbot, Scophthalmidae) were analysed electrophoretically at 17 common enzymatic loci in samples taken from 11 sites representing the species ranges in Europe. Brill showed a mean heterozygosity ( H ) of 0·11 while that of turbot was 0·02. The virtual absence of genetic diversity in turbot is probably due to a very low evolutionary rate, and provides little evidence for population substructure even if various signs indicate the possibility of a hidden differentiation (presence of the taxon maoetica in the Black Sea and differentiation of a species-specific cestode parasite on either side of the Strait of Gibraltar). On the other hand, the weak geographic structure in brill seems to result from rapid recolonization following the last ice age.