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     

An association of melanophores appearing at metamorphosis as vehicles of asymmetric skin color formation with pigment anomalies developed under hatchery conditions in the Japanese flounder, Paralichthys olivaceus

The mechanisms for asymmetric skin color formation in the Japanese flounder are studied with particular concerns to causes for pigment disorder (hypomelanosis) occurring under hatchery conditions. For an analysis of normal pigmentation, fish were raised with wild zooplanktons in an indoor hatchery, whilst for hypomelanosis, they were raised with Brazilian Artemia nauplii, a diet used in the hatcheries. Morphological observations, counting of melanophores, histochemical assay of DOPA-positive immature cells (melanoblasts), and radiometric estimation of tyrosinase activities in skins of developing larvae and juveniles indicate that 1) the structural plan for pigmentation in this species is bilaterally symmetric until metamorphosis, utilizing large-sized melanophores (hence larval melanophores) as main vehicles, and 2) an asymmetric coloration characteristic to metamorphosed juveniles is formed by an intensive development of smaller-sized melanophores (hence adult-type melanophores) appearing selectively in the ocular side at the later stages of metamorphosis and by an absence of it in the blind. These findings apparently indicate that 1) two types of melanophores occur in this species which differ with respect to morphological properties and developmental fate, and 2) selective differentiation of adult type melanophores in the ocular side of the body at or after metamorphosis is primarily responsible for an asymmetric coloration of its adult form. The similar assays on the fish fed with Artemia nauplii indicate that defective development of adult-type melanophores results in hypomelanosis in their ocular-sided skins, yielding a pigmentary pattern seen in the blind side of the metamorphosed juveniles with normal pigmentation.(ABSTRACT TRUNCATED AT 250 WORDS)     

蓝光诱导的胶孢炭疽菌(Colletotrichum gloeosporioides)类胡萝卜素积累

胶孢炭疽菌(Colletotrichumgloeosporioides)为一种丝状真菌,蓝光照射可诱导类胡萝卜素的积累。光镜下观察表明,蓝光可诱导胶孢炭疽菌菌丝积累色素颗粒,而黑暗和红光处理却无此现象。类胡萝卜素的积累受蓝光光照强度的影响。28℃且蓝光为6.5μmol.m-2.s-1时,类胡萝卜素积累量可随光照时间延长呈增长趋势,在第5天达到最高峰为71.8μg/g FW,随后含量下降。此外,胶孢炭疽菌在黑暗中预培养的时间也影响蓝光的诱导反应。     

Effects of Anoxia and Red Light on Changes Induced by Blue Light in the Membrane Potential of Pulvinar Motor Cells and Leaf Movement in Phaseolus vulgaris L.

In the dark, the membranes of the pulvinar motor cells of Phaseolusvulgaris L. were rapidly depolarized under anoxic conditionsand repolarized with re-aeration. This change in potential mayhave been due to suppression by anoxia of a respiration-dependent,electrogenic ion pump in the motor cells. When the pulvinuswas irradiated with blue light (BL) in the depolarized stateunder anoxic conditions, no marked depolarization occurred.Furthermore, a short pulse of BL did not induce transient depolarization.On continuous irradiation with red light (RL), the motor cellunder anoxic conditions showed slow recovery of the depolarizedmembrane potential. When a pulse of BL was superimposed on theRL after the recovery, transient depolarization occurred again. The leaf showed a small downward movement under anoxic conditionsbut recovered with re-aeration. Upward movement of the leafcaused by continuous application of BL to flexor cells changedto a downward movement under anoxic conditions, and re-aerationled to a return to upward movement. Unidirectional irradiationby BL of the flexor side did not cause upward movement of theleaf under anoxic conditions. However, unidirectional irradiationof RL to the flexor side caused downward movement of the leafunder anoxic conditions, which could be changed to upward movementby superimposition of irradiation with BL. The experimentalresults clearly show that BL acts mainly to inhibit (depolarize)an electrogenic component of the membrane potential in pulvinarmotor cells which is dependent on a supply of energy from respirationor photophsphorylation. (Received November 1, 1989; Accepted April 12, 1990)     

Growth, pigmentation and activity of juvenile Japanese eels in relation to temperature and fish size

The growth and activity of juvenile Japanese eels Anguilla japonica in different pigmentation stages from the glass eel to the elver stage were studied in the laboratory at 15, 20 and 25° C. The growth and activity of the eels were significantly influenced by both temperature and fish size. Growth rate generally declined with increasing fish size, and fish were least active and experienced a low growth during the pigmenting stage at all temperatures. They were nocturnal and spent significantly more time moving (swimming, feeding and moving over the substratum) at 20 and 25° C than at 15° C at night within each pigmentation stage. Accordingly, they grew significantly faster at 20 and 25° C than at 15° C throughout the study. The development of pigmentation appeared to be dependant on water temperature but not on fish size. This study suggested that the growth and activity of juvenile Japanese eels were positively correlated, because fish were least active and grew slowest at low temperature (15° C) or during the pigmenting stage at all temperatures.     

Food- and light-entrainable oscillators control feeding and locomotor activity rhythms, respectively, in the Japanese catfish, Plotosus japonicus

Feeding and locomotor activities of the Japanese catfish Plotosus japonicus under solitary condition were recorded to identify mechanisms controlling these behaviours. In the absence of food, the catfish showed nocturnal locomotor activity, but no feeding activity. Under ad libitum food conditions, both feeding and locomotor activities occurred during the dark period and were synchronized with light/dark (LD) cycles. Feeding activity lasted for 11–24 days when food was stopped after ad libitum food availability. Restricted food during the light phase produced both food-anticipatory and light-entrainable feeding activity. Furthermore, this condition produced weak food-anticipatory and light-entrainable locomotor activity. Under the light/light (LL) condition, restricted food produced food-anticipatory feeding and locomotor activities, suggesting that a food-entrainable oscillator controls both feeding and locomotor activities. However, under the LL condition, light-entrainable feeding and locomotor activities were not observed, suggesting that a light-entrainable oscillator controls both feeding and locomotor activities. During a restricted food schedule, LD cycle shifts resulted in disrupted synchronization of feeding activity onset in three of the four fish, but one fish showed synchronized feeding activity. These results suggest that the food- and the light-entrainable oscillator may control feeding and locomotor activities, respectively.     

Distribution of mucous cells on the body surface of Japanese flounder Paralichthys olivaceus

The distribution of mucous cells was examined in the skin on the ocular and blind sides of Japanese flounder Paralichthys olivaceus. Observations were performed on both body sides at the following regions: cheek, lower jaw (blind side), gill cover (ocular side), dorsal side, lateral line, belly and caudal peduncle. The mucous cells observed were elliptic and positively stained for periodic acid Schiff reaction and Mayer's mucicarmine and showed a higher density and larger size on the ocular side compared to the blind side. Low densities of mucous cells were observed on the lower jaw compared with other regions of the body. The depth of the crack located between scales was deeper on the ocular side than the blind side, which might reflect total epidermis area and total number of mucous cells. Bacterial infection elucidated some information on the effect on the density and size of mucous cells, where the density and size decreased slightly after infection. Only the lower jaw, however, showed an increased number of mucous cells. The results show that the potential of skin to secrete mucus is higher on the ocular than on the blind side and bacterial infection decreases mucous secretion.     

枸杞岛潮下带沙地生境鱼类群落结构和季节变化

为了解岛礁水域沙地生境的鱼类群落结构特征,评估该生境对鱼类资源养护的潜在作用,于2009年采用多网目组合刺网对枸杞岛潮下带沙质区域进行了逐月采样,同步设置岩礁为对照生境.应用α和β多样性指数结合相对重要性指数、相对渔获率、ABC曲线和聚类排序方法对两种生境中的鱼类组成、多样性变化和群落格局与变化进行了全面探讨.全年在沙地和岩礁生境共采集鱼类63种,隶属11目38科56属,2种生境各自出现的鱼类皆为46种.受暖水种频繁出现在沙地生境的影响,潮下带沙质区域鱼类区系比岩礁生境略显丰富,且春夏季的渔获量普遍高于岩礁生境;由于种类组成均匀度较低,沙地生境各季节的α多样性普遍较低,夏季显著低于岩礁生境.日本须鳎是沙地生境的指示种,为早春、夏末和秋冬季沙地底层优势鱼种.5-7月鳀、多数月份鲻和10月份鳗鲇等种类对沙地生境的阶段性利用,使其形成了区别于以趋礁性鱼类为优势类群的岩礁生境的群落格局和季节动态.沙地是多种鱼类幼鱼阶段的庇护所和饵料场,是鲆鲽类的良好栖息地.沙地生境在维持鱼类区系和养护鱼类资源方面具有重要作用.     

Distinct Melanogenic Response of Human Melanocytes in Mono‐culture,in Co‐Culture with Keratinocytes and in Reconstructed Epidermis,to UV Exposure

Striking differences are observed in the melanogenic response of normal human melanocytes to UVA and UVB irradiation depending on culture conditions and the presence of keratinocytes. Exposure of melanocytes co‐cultured with keratinocytes to UVB irradiation triggered, already at low doses (5 mJ/cm²), an increase in melanin synthesis whereas in melanocyte mono‐cultures, UVB doses up to 50 mJ/cm² had no melanogenic effect. Unlike UVB, UVA exposure caused the same melanogenic response in both mono‐ and co‐cultures. Removing certain keratinocyte growth factors from the co‐culture medium abolished the melanogenic response to UVB, but not to UVA exposure. When integrated into the basal layer of a reconstructed human epidermis, human melanocytes similarly reacted to UVA and UVB irradiation as in vivo by increasing their production and transfer of melanin to the neighboring keratinocytes which resulted in a noticeable tanning of the reconstructed epidermis. The presence of a dense stratum corneum, known to scatter and absorb UV light, is responsible for higher minimal UVB and UVA doses required to trigger a melanogenic response in the reconstructed epidermis compared to keratinocyte–melanocyte co‐cultures. Furthermore, an immediate tanning response was observed in the pigmented epidermis following UVA irradiation. From these results we conclude that: (i) keratinocytes play an important role in mediating UVB‐induced pigmentation, (ii) UVA‐induced pigmentation is the result of a rather direct effect on melanocytes and (iii) reconstructed pigmented epidermis is the most appropriate model to study UV‐induced pigmentation in vitro.     

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.     

Mechanism of vestibular adaptation of fish under microgravity.

In a space experiment, the adaptation of goldfish behavior during flight and readaptation after landing were investigated. Six goldfish (1 normal, 1 with otoliths removed on both sides, 4 with otoliths removed on one side) were flown in a fish package (F/P) of Aquatic Animal Experiment Unit (AAEU). The dorsal light responses (DLRs) of fish with otoliths removed were recorded after operation until launch and after landing. The behaviors of the fish were recorded with a video camera on Mission Elapsed Time (MET) Day-00, 02, 05, 08, 12. On MET Day-00, two fish with otoliths removed on one side showed flexion of body toward the operated side. These fish also showed rolling behavior toward the operated side. However, the body flexion disappeared on MET Day-05 or MET Day-08. No rolling behaviors were observed after that time. Five fish showed backward looping behaviors during the mission. Although the frequency of looping episodes decreased after MET Day-08, five fish still showed looping behavior on MET Day-12, that was the last day of video recording on orbit. In microgravity, visual system of fish did not seem to provide sufficient cues to prevent them from looping or rolling. After landing, no looping and rolling behavior was observed. However, the tilt angle of the DLR increased in the fish with otolith removed 5 month before launch but not in normal fish and those with otoliths removed 2 weeks before launch. These results suggest that the behavioral dysfunction and the adaptational process in space are dependent on vestibular inputs.     

The importance of carotenoids in signaling during aggressive interactions between male firemouth cichlids (Cichlasoma meeki)

Male firemouth cichlids, Cichlasoma meeki, have red pigmentationcovering large areas of their ventral surface, which is displayedduring aggressive interactions. We manipulated the levels ofred pigmentation by assigning the fish to one of two diets,which were as similar as possible except that one was high incarotenoids while the other was low in carotenoids. During diadictrials under white light, fish kept on the high carotenoid dietwon a higher proportion of contests than fish kept on the lowcarotenoid diet Under green light, where differences in rednesscannot be discriminated, there was no effect of diet on theoutcome of contests. These experiments demonstrate that it isthe effect of the diet on red pigmentation that is importantrather than some confounding variable such as differential growthrates. The weight of the two fish was also important; therewas a tendency for the heavier fish to win more contests. Themass effect was subordinate to color under white light but wasthe dominant factor under green light The nature of the contestsunder the different light conditions also varied; the displayin which the red pigmentation is most obvious was not used undergreen light, but was common under white light This suggeststhat the display strategies are flexible and can be alteredaccording to which displays are most effective in a given environmentPrevious studies of other species of fish and birds have shownthat the degree of redness influences mate choice and is affectedby parasite infestations. We propose that carotenoid pigmentationis likely to reflect a general quality, influenced by severalfactors, rather than a context-specific quality such as fightingability.     

Analysis of growth during light-induced hook opening in cress

Abstract. Growth in various regions of the hypocotyls of dark-grown cress seedlings before and after exposure lo continuous white light has been analysed by time-lapse photography. In the dark, growth in the hook was minimal, the upward growth of the seedling being sustained by extension of the shank, especially the uppermost zones. Following irradiation, the hook and the remainder of the hypocotyl showed dissimilar growth responses. Previously growing regions of the shank were inhibited while zones within the hook, especially the apical end of the inner (concave) side, showed marked growth stimulation. These changes in growth rates commenced within 1 h from exposure to the light stimulus and thus considerably preceded any observable changes in hook angle.     

Der Micos-Fisch,Höhlenfisch in statu nascendi oder Bastard ?

The Micos Population–cave fish in statu nascendi or hybrid? Observations on the evolution of cavernicoles The Micos-Cave in the Sierra de la Colmena in the State of San Luis Potosi, Mexico, contains a cavernicolous population of Astyanax mexicanus, whose members are for the most part blind, but, in contrast to other cave dwelling populations of the same species, appear almost normal in their pigmentation. Besides these, there are also large eyed and pigmented specimens to be found in this cave. Any transitional stages between the blind and the normal visioned fish are lacking. Offspring of the blind cavernicoles that are raised under light conditions develop a superficially lying eye which is markedly smaller than normal, attaining its size proportional to the light-intensity of the experimental conditions. The size and structure of the eye-remnants of the blind fish as well as the eyes of their offspring are considerably more variable than in the river specimens. Crossings of the blind Micos fish with the river fish Astyanax and also with a blind and unpigmented troglobiont of the same species - Sabinos fish - result in both cases in a more or less intermediate F¹-hybrid. A strict inbreeding within the Micos fish, selecting specimens with especially large eyes, produced animals whose eyes are comparable to those of the river fish after only three offspring generations. Electrophoresis studies on the allozyme variability at various loci prove that the Micos fish is genetically only slightly different compared to the river fish. On the other hand in some allele frequencies there is an alternative variation between the two. The Micos fish also differs from the typical troglobionts which are monomorphic at almost all loci examined and also possess alleles that are not found in the river form. Based on the genetic constitution, the Micos fish and the river fish found in the cave do not form a panmictic population. It is also doubtful that the Micos fish is the progeny of a hybrid swarm which previously resulted from a cross between a real troglobiont and the newly arrived river fish, because the Micos fish is in every characteristic genetically very similar to the river fish, whereas no clear traces of troglobiont relationship are found. Thus the Micos fish actually appears to be a cave form in statu nascendi against which the river fish that find their way in from time to time cannot compete.     

Photoreactivating enzyme in the blind cave fish, Anoptichthys jordani.

1. Exposure of cells to ultraviolet light induces molecular changes in DNA which may lead to cellular death. 2. One product, pyrimidine dimers, is reversed during subsequent exposure to visible light by photoreactivating enzyme. 3. Photoreactivating enzyme has been recorded in different organisms, but inconsistencies in its distribution suggest it may have other functions. 4. We have found photoreactivating enzyme in the blind cave dwelling fish, Anoptichthys jordani. 5. Sufficient time has elapsed in the cave environment to allow loss of features of importance to epigean fish, including the eyes and pigmentation. 6. The continued presence of the enzyme indicates that it may have other functions.     

Importance of sandy bottoms in coral reefs to the oscillation of daily rhythms in the tropical wrasse Halichoeres trimaculatus

Most wrasse species swim during the day and bury themselves in the sandy bottoms of shallow reefs at night. This study aimed to evaluate the importance of sandy bottoms to the day-active/night-inactive rhythmicity of the tropical wrasse Halichoeres trimaculatus. Actogram analysis revealed that fish were active during the photophase and inactive during the scotophase in aquariums with both sandy and bare bottoms. When fish were kept in aquariums with bare bottoms, rhythmicity was maintained under constant dark conditions (DD) but became obscured under constant light conditions (LL), suggesting that a day-active/night-inactive rhythmicity is regulated by the circadian system. Robust fluctuations in Period1 (wPer1) and Period2 (wPer2) expression were observed in the pectoral fin tissue under light–dark conditions (LD). Similar fluctuations in wPer1 expression persisted under DD. When fish were kept under LD conditions for 7 days and then DD for 20 days, the emergence of fish from the sandy bottom was delayed gradually. At the same time, the peak time of wPer1 expression under DD was retarded from 06:00 to 10:00. Although wPer2 expression was dampened under DD, it increased after exposing fish to light. These results suggest that wPer1 and wPer2 are differentially involved in the day-active/night-inactive rhythmicity, and that blocking light with a sandy bed at night and exposing fish to light during emergence in the morning play important roles in maintaining consistent activities in wrasse species.     

Pigmentation development in hatchery-reared flatfishes

Malpigmentation is common in hatchery-reared flatfishes, decreasing the market value of whole fish, and increasing the risk of predation for juveniles released to enhance wild stocks. Pigmentation development in flatfishes occurs in two phases. First, during embryonic and larval stages pigment cells differentiate on both sides of the body. Second, at metamorphosis larval melanophores disappear, and adult melanophores differentiate on the ocular but not on the blind side. Malpigmentation seems to result from disruptions of the second phase, and may take the form of albinism on the ocular side or darkening of the blind side. Both types of aberration may be related to aspects of the hatchery environment such as lighting, substratum, and diet. Larval nutrition appears to be a key factor and enrichment of larval diets with fatty acids and Vitamin A can greatly reduce malpigmentation rates; however, levels suffcient to prevent pigmentation defects frequently cause other abnormalities. Two developmental explanations for albinism have been proposed. The first is that differentiation of ocular-side skin follows the normal blind-side pathway and adult melanophores therefore fail to develop on the ocular side. The second hypothesis suggests that dietary deficiencies inhibit retinal development and the resulting visual defects lead to failure of a hormonal signal required for melanophore differentiation. These hypotheses may well be complementary; as yet neither has been thoroughly tested. Definitive tests will require a combination of manipulative techniques such as tissue transplantation and cell culture with nutritional, behavioural and hormonal assays. Such integrative studies will further the understanding both of normal pigmentation development and of the environmental factors that contribute to high rates of albinism in hatchery-reared flatfish.     

Phylogenetic analysis of betanodaviruses isolated from cultured fish in Korea

Since the publication of the first report on fish nodaviruses in Korea in 1998, fish nodaviruses have caused widespread epizootic events among various fish species in Korea. However, the genotypes of fish nodaviruses in Korea have not yet been determined due to a lack of information about their nucleotide sequences. In this study, we isolated 5 fish nodaviruses from 4 fish species cultured in 4 different regions in Korea: rock bream Oplegnathus fasciatus, Japanese flounder Paralichthys olivaceus, sevenband grouper Epinephelus septemfasciatus, and grey mullet Mugil cophalus. The full open-reading frame (ORF) encoding the coat protein (1017 nt) was sequenced from each of the 5 fish nodaviruses and the nucleotide sequences were phylogenetically analyzed. Results showed that even though their sequences were not identical, all 5 Korean isolates were clustered in the RGNNV genotype. This is the first report on the phylogenetic analysis of fish nodaviruses from cultured fish in Korea.     

Process of pigment cell differentiation in skin on the left and right sides of the Japanese flounder,Paralichthys olivaceus,during metamorphosis

Two groups of larvae of the Japanese flounder,Paralichthys olivaceus, were reared in the laboratory. The survivors of the first group (normal) showed normal pigmentation, and the second group (albinic) exhibited nearly complete pseudoalbinism after metamorphosis. The process of pigment cell differentiation on the left and right sides was observed mainly by transmission electron microscope (TEM) in relation to metamorphosis. In the normal group, chromatoblasts in the left side skin differentiated successfully, but those in the right side skin showed shrinkage and collapse during metamorphosis. Mucus cells are known as typical cells of ocular side skin in flatfish. The ratio of mucus cell density (left side/right side) increased from the onset of metamorphosis. These results suggest, some components of skin changed asymmetrically in process of metamorphosis before differences in fine structures of chromatoblasts were detected between the left and right sides of the normal group. However, in the albinic group, the same process of chromatoblast collapse occurred on the left and right sides, and there was no change in the ratio of mucus cell density during metamorphosis.