Melanophore comparisons in different forms of ambicoloration in the flatfish Pseudopleuronectes americanus and Reinhardtius hippoglossoides

The melanophores associated with contrasting manifestations of ambicoloration in two species, winter flounder ( Pseudopleuronectes americanus ) and Greenland halibut ( Reinhardtius hippoglossoides ), from the Pleuronectidae are compared microscopically. Winter flounder is a benthic inshore species, whilst Greenland halibut is a deep water species considered to spend the greater part of its life away from the sea floor, although the relatively thick blind-side epidermis associated with a benthic life occurs in both species. Various forms of abnormal ambicoloration occur in some specimens of winter flounder. Melanophores from the flounder blind side are morphologically similar to those from the ocular side in the different forms of ambicoloration, although there are differences in melanophore densities. In Greenland halibut, ambicoloration is a normal characteristic which is considered to be secondarily acquired. The melanophores of the ocular side of Greenland halibut are similar to the melanophores of other Pleuronectidae, whereas those of the blind side are very different in morphology and size.     

Observations on anomalous conditions in some flatfishes (Pisces: Pleuronectiformes), with a new record of partial albinism

Synopsis Abnormalities in five specimens of pleuronectiform flatfishes (one specimen from the family Soleidae, four from Bothidae) are described. The account of naturally occurring anomalies in the naked sole,Gymnachirus melas, is the first from the western Atlantic for a soleid other thanTrinectes maculatus. Anomalies inG. melas include partial albinism and osteological deformities. A second account of pigment and morphological aberrations is provided forParalichthys albigutta (total ambicoloration, incomplete eye rotation and hooked dorsal fin). Partial ambicoloration is reported for three specimens ofParalichthys lethostigma. Possible causes of abnormalities in flatfishes are reviewed. It is postulated that minimum depth of occurrence of species may be linked to frequency of abnormalities. Anomalies appear to be most frequent in species and families of flatfishes which inhabit shallow coastal or estuarine (<5 m depth) waters.     

Saddleback Deformities in Fish Species Collected from the Arabian Gulf Coast of Jubail City,Saudi Arabia

The saddleback syndromes were observed in several commercial fishes obtained from Saudi Arabian coast of the Arabian Gulf. These deformities resulting in missing dorsal spines or rays, sometimes accompanied by a depression in the dorsal profile, were found in ten fish species from seven families. Other morphological abnormalities such as scale disturbances, lateral line deformity, and kyphosis, the presence of a lesion, slight ambicoloration, and supraneural deformities accompanying the saddleback deformity were also observed. The occurrence of similar deformities across such a spectrum of fishes from the same location suggests that the abnormalities were induced by something in the environment common to all these species.     

体色异常褐牙鲆皮肤色素及鳞片发育的形态学研究

本文观察比较了体色正常及体色异常褐牙鲆 (Paralichthysolivaceus)皮肤中黑色素胞和鳞片的发生及演变过程。结果显示仔鱼鱼体两侧皮肤中最先出现星状幼体型黑色素胞 ,随着变态发育 ,有眼侧皮肤中成体型黑色素胞逐渐替代幼体型黑色素胞 ;而无眼侧皮肤中 ,幼体型黑色素胞逐渐退化崩解 ,成体型黑色素胞不出现 ,无眼侧皮肤逐渐失去色素变为白色。体色异常现象出现于变态后期 ,白化和黑化现象几乎同时发生。白化个体有眼侧皮肤中成体型黑色素胞不能正常替代幼体型黑色素胞 ,逐渐失去色素形成白色斑块。黑化个体无眼侧皮肤中成体型黑色素胞则非正常地出现 ,逐渐替代幼体黑色素胞形成黑斑。约 30日龄变态完成时 ,体色异常现象已经显著 ,已能明显区分体色正常和异常个体。 6 0日龄左右 ,幼鱼皮肤开始长出形态较为原始的圆鳞。体色正常个体有眼侧皮肤上的圆鳞会逐渐发育成栉鳞 ,无眼侧则维持圆鳞。对比分析体色异常个体的鳞片形态 ,发现有眼侧白化部位的鳞片仍为圆鳞 ,而无眼侧黑化部位的鳞片则发育为栉鳞。同时 ,通过对体色正在恢复中的白化牙鲆的鳞片观察表明 ,伴随着白化部位色素的恢复 ,该部位的圆鳞会逐渐转变为栉鳞。由此推断色素的发生与鳞片的发育密切相关     

Chromatophore distribution and inferior performance of albino Japanese flounder Paralichthys olivaceus with special reference to different chromatophore expression between albinism and pseudo-albinism

Albinism with a large variation in body color was found in a hatchery population of Japanese flounder. In addition to albinism, ambicoloration and pseudo-albinism were simultaneously observed in some individuals. Albinos had a remarkably lower number of melanophores on the scales of ocular side than wild-type individuals did, although no significant difference was observed in the numbers of xanthophores and iridophores. The intensity of body color significantly correlated with the number of melanophores among the albinos. No significant differences were observed in the intensity of body color and the number of melanophores between the ocular side and the ambicoloration area. Pseudo-albinism was accompanied by the reductions of melanophores and xanthophores, indicating the different expression patterns of chromatophores between albinism and pseudo-albinism. The combined effects of albinism and pseudo-albinism caused the disappearances of melanophores and xanthophores in the pseudo-albinism area of albinos. In addition to chromatophores, the different characteristics of several phenotypic traits were observed between albinos and wild-type individuals. Growth-related traits of the albinos were inferior to those of the wild-type individuals. Furthermore, the albinos had a larger pseudo-albinism area and a higher vertebral deformed rate than the wild-type individuals did. Individual multilocus heterozygosity and inbreeding coefficient measured by microsatellite loci did not show any indication that the albinos had higher inbreeding coefficient than the wild-type individuals did. This study demonstrated the expression patterns of chromatophores in the body color abnormalities of a flatfish species and the potential pleiotropic effects of an albinism gene on some phenotypic traits.     

Effects of sandy substrate and light on hypermelanosis of the blind side in cultured Japanese flounder Paralichthys olivaceus

Rearing experiments were carried out to clarify the effects of sandy substrate and light irradiation on hypermelanosis of the blind side (the staining type of ambicoloration) in cultured Japanese flounder. Fish were reared in three experimental conditions: (1) no sandy substrate into which fish could bury themselves and with upward light irradiating their blind sides, (2) no sandy substrate and no upward light, and (3) sandy substrate (transparent glass sand) with upward light irradiation. Pigmented areas on the blind side were measured by an image analyzing system. Flounder from the third condition (sandy substrate with light irradiation) showed the lowest pigmentation on the blind side. In contrast, fish from the second condition (no sandy substrate and no light irradiation), showed the highest pigmentation coverage. These results indicate that sandy substrate on the bottom in culture tanks is more important than light irradiation as a factor affecting hypermelanosis of the blind side in cultured Japanese flounder.     

Induction of ambicoloration by exogenous cortisol during metamorphosis of spotted halibut Verasper variegatus

Cortisol, the main glucocorticoid in fish, increases during flatfish metamorphosis and peaks before the surge of thyroxine. A large body of evidence indicates the essential role of thyroxine in flatfish metamorphosis, whereas information on cortisol is limited. We administered cortisol to spotted halibut Verasper variegatus larvae in order to examine the effect on pigmentation during metamorphosis. Administration of 10 μg cortisol per mL of water from before the onset of metamorphosis (stage E) to metamorphic climax (stage G) induced the development of adult type pigment cells on the blind side of the metamorphosed juveniles and increased the occurrence of ambicolored juveniles. When 10 μg/mL cortisol was administered during stage D, stages E–F, stage G or stage H, only the administration during stages E–F induced the development of adult type pigment cells on the blind side. In addition, the expression of the gene dopachrome tautomerase (dct), a marker of melanoblasts, was enhanced at Stage E by cortisol administration. These results clearly indicated, for the first time, the enhancement of pigmentation by exogenous high-dose cortisol. Since endogenous cortisol is secreted in response to various kinds of stress in rearing conditions, these results indicate a possible influence of stress conditions in the occurrence of ambicoloration in flatfish.     

果实膨大期喷布磷酸二氢钾对三月红荔枝果实贮藏性的影响

在三月红荔枝(Litchi chinensis cv.Sanyuehong)果实膨大期对树冠喷施0.2%磷酸二氢钾(KP)水溶液,以探讨磷酸二氢钾对荔枝果实贮藏性的影响。结果表明:(1) KP处理的果实在贮藏期前17d,失重率及果肉可溶性固形物、酸、VitC、花色素苷等指标的变化趋势与对照基本相似;(2) KP处理的果肉可溶性蛋白质含量变化与对照有明显差异,而果皮的可溶性蛋白质含量在贮藏期前10d变化动态与对照一致,此后呈相反的变化趋势;(3)果皮POD活性显著高于果肉,KP处理和对照的果肉POD活性在贮藏第3d后、果皮POD活性在第17d前分别具有相似变化趋势;(4)果肉中CAT活性在贮藏第3~17d期间都显著或极显著高于果皮,KP处理和对照果肉、果皮CAT活性动态变化均为单峰曲线。     

Influence of in vitro factors on titre and elimination of model fruit tree viruses

The titre of apple chlorotic leaf spot virus (ACLSV) was higher in microplants of Malus domestica cv. Jonagold than in 2-year-old grafted scions. Cytokinin concentration in the medium increased the titre of prunus necrotic ringspot virus (PNRSV) in the apex of microplants of Prunus insititia cv. Kozlienka but did not affect the titre of ACLSV in M .domestica.Virus titre of ACLSVwas higher in the haulms of autotrophically-grown compared with heterotrophically-grown microplants whereas as for PNRSV the results were the reverse. For both viruses, however, titre of the virus in the roots of autotrophically-grown plants was significantly higher than in haulm tissue from heterotrophic cultures. Ribavirin incorporation resulted in elimination of both viruses. Negative ELISA results were confirmed independently by PCR. The efficacy of Ribavirin in elimination of ACLSV was increased by increasing the concentration of cytokinin in the medium in parallel with decreasing the concentration of Ribavirin. These results are discussed in the context of the reliability of in vitro virus testing.     

Rat brain thioltransferase: regional distribution, immunological characterization, and localization by fluorescent in situ hybridization

Thioltransferase (TTase) is a member of the family of thiol-disulfide oxidoreductases that are involved in the maintenance of sulfhydryl homeostasis in cells by catalyzing thiol-disulfide interchange reactions. One of the major consequences of oxidative stress in brain is the formation of protein-glutathione mixed disulfides (through oxidation of protein thiols), which can be reversed by TTase during the recovery of brain from oxidative stress. We therefore examined the presence of TTase in brain regions from rat. In the rat, TTase activity in the whole brain was comparable with the corresponding activity in liver, but significantly higher in hippocampus. The enzyme activity was significantly lower in striatum and cerebellum compared with activity in whole brain. Rat brain TTase shared immunological similarity with the human red blood cell enzyme, but not with the pig liver enzyme. The constitutive expression of the mRNA to TTase was demonstrable by northern blotting. Localization of the TTase mRNA in rat brain by fluorescent in situ hybridization showed the presence of high amounts of mRNA in the olfactory bulb, cortex, and hippocampus and its predominant localization in the neurons. TTase mRNA was also present in Purkinje cells in the cerebellum, in giant reticular neurons in the midbrain, and in the striatal and thalamic neurons. This study demonstrates the constitutive presence of a functional TTase system in brain and delineates the regional and cellular localization of the enzyme in rat brain.     

Circadian rhythmic changes in the lipid composition of muscles in kilka <Emphasis Type="Italic">Clupeonella cultriventris</Emphasis> (Clupeidae,clupeiformes) during natural periodicity of feeding in the feeding and spawning periods in the Rybinsk Reservoir

According to data of observations in 2002–2004, differences in the pattern of diurnal fluctuations in the total content and fractional composition of lipids in muscles of mature specimens of kilka Clupeonella cultriventris from the Rybinsk Reservoir in the feeding and spawning periods were revealed. It was established that the feeding intensity in kilka considerably changes throughout 24 h in both periods of the annual cycle, while diurnal fluctuations in the fatness of muscles are distinctly manifested only in the reproductive period and have a dissimilar pattern in specimens of different sexes. In females and males, they are determined mainly by the change in the content of the fraction of reserve lipids-triacylglycerols, as a rule, by its increase in the light hours of the day, several hours after an increase in the feeding activity of fish. The pattern of diurnal fluctuations of the level of lipid fractions (phospholipids, triacylglycerols, cholesterol, and its ethers) in kilka’s muscles differs from that in the feeding period. Possible causes of the change of diurnal variations of the considered indices of lipid metabolism in kilka at an increase in the endocrine activity of its body in the reproductive period is discussed.     

Distribution and Abundance of Primates in Rain Forests of the Western Ghats,Karnataka, India and the Conservation of Macaca silenus

We assessed the distribution and abundance of 4 species of diurnal primates viz. lion-tailed macaque, bonnet macaque, Nilgiri langur and Hanuman langur, in 2 areas—Brahmagiri-Makut and Sirsi-Honnavara—in rain forests of the Western Ghats in the state of Karnataka, India. The Nilgiri langurs in Brahmagiri-Makut and the lion-tailed macaques in Sirsi-Honnavara are the northernmost populations of the 2 species in the Western Ghats. The 2 regions represent changes in ecological zones in the Western Ghats. In Brahmagiri-Makut, Hanuman langurs and bonnet macaques occupy lower elevations whereas Nilgiri langurs live in relatively higher altitudes. Only one group of lion-tailed macaques was in Brahmagiri-Makut. In the forests of Sirsi-Honnavara, 3 species of primates viz. lion-tailed macaque, bonnet macaque and Hanuman langur were in larger numbers throughout the forest. A self-sustainable single population of 32 groups of lion-tailed macaques occurred in Sirsi-Honnavara. Few subspecies of Hanuman langurs exist in the study regions. Due to local hunting practices, the relative abundance of primates in Brahmagiri-Makut is lower than that in Sirsi-Honnavara.     

Investigation on the Ontogeny of Pollen in Pinus thunbergii Parl

The microsporogenesis in Pinus thunbergii occurs in early to middle March, and the development of pollen in late March to early April. A mature pollen grain consists of four cells. The starch grains aggregate in the equators during meiosis Ⅰ to Ⅱ. The callose materials appear first in inner side of the wall of meiocyte and then in the equator. Sometimes the 3-or 4-sac- cate pollen grains have been found. In the ontogeny of pollen in Pinus thunbergii following events are noteworthy. (1) During meiosis the equatorial aggregation of starch grains in me iocyte becomes conspicuous. (2) During formation of tetrad the callose wall appears in regular activity. It is noteworthy that there is itself feature for the accumulation of callose in Pinus thunbergii. After formation of prothallial cells the callose appears mainly in the area between body and saccus. So the prominent symmetry of distribution of callose occurs in the pollen grains. But almost no callose accumulation takes place i,n tenuity in distal face of pollen grain. On the contrary, there are certain callose accumulation around the prothallial cells in the proximal face, forming the polar distribution of callose in pollen grains.     

Effect of Moniliformis moniliformis density on distribution within the definitive host population (Rattus norvegicus)

The population dynamics of Moniliformis moniliformis was studied in ‘free-ranging’ laboratory rats, Rattus norvegicus, presented with different relative density levels of M. moniliformis in cockroaches, Periplaneta americana. Changes in selected population parameters of the negative binomial distribution were evaluated as indicators of changes in aggregation. A significant increase in the degree of aggregation of parasites occurred as a result of the increase in relative density of infective stages available to the rats. This increase in aggregation was due to the increase in over-dispersion that occurred in female rats only. The degree of aggregation in females was found to be significantly higher than that in males at both treatment levels. The best indicators of the degree of aggregation were found to be the ratio of the variance to the relative density and the ratio of the log-variance to log-relative density. Changes in k were not correlated with changes in over-dispersion or the relative density.     

Structure, distribution and physiological functions of ghrelin in fish

Ghrelin was originally purified and characterized in rats and humans as the first identified endogenous ligand of the growth hormone secretagogue receptor. In mammals, ghrelin is mainly produced in the stomach, with minor levels of ghrelin present in the brain and various other tissues. Ghrelin is involved in the regulation of many physiological functions including the regulation of growth hormone secretion and food intake in mammals. The gene and peptide structures of ghrelin have been recently identified in several fish species. As in mammals, ghrelin mRNA is mainly expressed in the gut of fish. Ghrelin is involved in the regulation of a number of physiological functions, including the regulation of pituitary hormone release and the stimulation of food intake in fish. In this review, we wish to provide an up-to-date discussion on the structure, distribution and functions of ghrelin in fish, in comparison to ghrelin in other vertebrates.     

The effect of periovulatory imbalance of prolactin on the expression of prolactin receptors in rat ovary cells

Using the technique of immunohistochemistry in combination with cytophotometry, we have studied the effect of periovulatory hyper- and hypoprolactinemia on the expression of prolactin receptors in various cell types of rat ovaries during early estrus. It has been shown that intense specific staining of oocytes is positively controlled by prolactin. The maximal intensity of specific staining was found in cells of the cumulus and the inner layer of granulosa cells in mature follicles; staining intensity gradually diminished towards the outer boundary cell layer. Postovulatory follicles are distinct from those mature follicles in which there was no ovulation in their more intense manifestation of prolactin receptors in cells of the inner layer and cumulus, as well as in increased positive staining (after prolactin administration) only in the granulosa layer cells closest to theca. In follicles which did not ovulate by the time of the early estrus, prolactin administration leads to a proportional growth of specific immunoreactivity in all cell layers of the granulosa. The administration of bromocryptin, an inhibitor of prolactin secretion, leading to a 10-fold decrease in the prolactin level in the blood, results in a twofold decrease in the intensity of specific staining of all cell layers of the granulosa in either type of follicle. Corpora lutea of the previous cycle have irregularly positioned luteocytes with weak and strong specific staining, the intensity of which is not changed in response to prolactin and diminishes slightly after the administration of bromocryptin. We conclude that the most intense changes in the content of prolactin receptors under the conditions of imbalance of this hormone during the periovulatory period are observed in those follicles where the oocyte did not ovulate by the time of early estrus.     

Modification of chemical properties of cell wall polysaccharides in the inner tissues by white light in relation to the decrease in tissue tension in Pisum sativum epicotyls

When white light irradiation inhibits shoot growth in derooted pea ( Pisum sativum L. cv. Alaska) cuttings, it decreases tissue tension, a driving force for shoot growth, by making the cell wall of the inner tissues mechanically rigid. To elucidate the mechanism by which light affects the mechanical properties of the cell wall in the inner tissues, its effect on the chemical properties of the cell walls was studied by analyzing qualitatively and quantitatively cell wall polysaccharides in the epdidermis and inner tissue of pea epicotyls grown in both dark and light. The amount of polysaccharides per subhook in the cell walls of both tissues increased during a 4-h dark incubation. Light suppressed the increase in hemicellulosic (HC)-II and cellulosic polysaccharides in the inner tissues, while it did not affect the increase in other wall fractions in either the epidermal or subepidermal tissues. No light effect was observed on the neutral sugar compositions of pectin, HC-I or HC-II fractions in either of the tissues. Light increased the mass-average molecular mass of xyloglucan and rhamnoarabinogalactan in HC-II fractions in the inner tissues, while such an effect was not observed in the epidermis. These facts suggest that the light-induced decrease in the tissue tension in pea epicotyls is caused by an increase in the molecular size of xyloglucan, rhamnoarabinogalactan in the HC-II fraction and/or the suppression of the synthesis of HC-II and cellulosic polysaccharides in the inner tissues.     

Ultrastructure and Lipase Activity of Cotyledon cell During Pod Development in Peanut

A series of significant changes of the ultrastructure and lipase activity of cotyledon cell were found in peanut (Arachis hypogaea) during pod development. In he initial stage of cotyledon development there were many plastids which kept producing starch grain and there were low lipase activity and very few lipid and protein bodies in the cell. In the middle stage of cotyledon development, a great number of larger lipid bodies were seen in the cell and a lot of protein bodies formed in the vacuoles and continued to increase in size. Lipase activity increased in the cytoplasm, endoplasmic reticulum, protein bodies, plasmalemma and intercellular space. In the later stage of cotyledon development, the lipid bodies did not increase in number but became slightly larger. The protein bodies continued to increase both in number and in size. Lipase acttvity was even hegher in the cytoplasm. In the final stage the protein bodies became irregular in shape and some of them tended to disintegrate with their content entered into the space around the lipid bodies. The lipase activity in the cell declined. The results indicated that the lipid body originated in the cytoplasm and the protein body originated in the vacuole; that the accumulation of oil and protein in peanut cotyledon resulted from the formation and development of lipid and protein bodies in the cell, and that the changes of plasmid and lipase activity in the cell played a role in the development of lipid body during the development of cotyledon.     

Relationship Between the Ubiquitin-Dependent Pathway and Apoptosis in Different Cells of the Central Nervous System: Effect of Thyroid Hormones

We have recently shown that sustained neonatal hyperthyroidism in the rat activates apoptosis of oligodendroglial cells (OLGc) and that inhibition of the proteasome-ubiquitin (Ub) pathway by lactacystin produces increased apoptosis in cerebellar granule cells (CGC). In the present study we have analyzed the relationship between the activation of the Ub-dependent pathway, the expression of the Ub genes and programmed cell death in neurons of the rat cerebellum and cerebral cortex and in OLGc. This study was carried out in normal animals, in rats submitted to sustained neonatal hyperthyroidism and in cell cultures treated with an excess of thyroid hormones. In neurons of the cerebral cortex, thyroid hormone produces an increase of Ub-protein conjugates, an enhancement in the expression of the Ub genes and an increase in apoptosis, while the opposite results are obtained in CGC. These results indicate that in neurons, the changes in the cell death program produced by thyroid hormone run in parallel with those occurring in the Ub-dependent pathway. In OLGc, thyroid hormone increases apoptosis but does not produce changes in the Ub pathway. Preliminary studies indicate that in coincidence with what occurs in optic nerves, the sciatic nerves both in controls and in hyperthyroid animals are unable to form Ub-protein conjugates. These results indicate that in cells of the CNS such as neurons, in which the Ub-dependent pathway is actively expressed, it appears to be closely correlated with apoptosis.     

The invasion of an introduced predator,Nile perch (<Emphasis Type="Italic">Lates niloticus</Emphasis>, L.) in Lake Victoria (East Africa): chronology and causes

Nile perch, a large predatory fish, was introduced into Lake Victoria in 1954. The upsurge of Nile perch in Lake Victoria was first observed in the Nyanza Gulf, Kenya, in 1979. In Ugandan waters this occurred 2–3 years later and in the Tanzanian Mwanza Gulf 4–5 years later. At the beginning of the upsurge in the Mwanza Gulf in 1983/1984 only sub-adult and adult fishes were found. The first juveniles appeared in 1985, suggesting that the initial increase of Nile perch was mainly caused by migration of sub-adults and adults. Shortly after the onset of trawl fishery in the area in 1973, haplochromines in the Mwanza Gulf started to decline. The final disappearance of the haplochromines, in 1987, only occurred after the Nile perch boom, and despite the abandoning of the haplochromine fishery in 1986. We hypothesize that the decline of haplochromines decreased predation on and competition with juvenile Nile perch and then facilitated survival of these juveniles. Consequently the immigration of sub-adult and adult Nile perch in an area may have paved the way for successful recruitment. Over-exploitation of haplochromine cichlids in the 1970s in the Nyanza Gulf, where the Nile perch upsurge was first observed, may have played a similar role.