摘要:

RésuméAu cours des quinze dernières années, les spermatozoïdes et le liquide séminal des poissons téliostéens ont fait l'objet de nombreux travaux dans le but de comprendre les processus mécaniques et chimiqes régulateurs de la motilité. Les spermatozoïdes de truite et de carpe ont été plus articulièrement étujiés; leur flagelle est du type classique “9 + 2” doublets de microtubules auquels sont associés des bras internes et externes de dynéine. Les battements flaellaires sont engendrés par des cycles d' accrochage/ décrochage des bras de dynéine d'un microtubufe au microtubule adjacent, l'énergie provenant de I'hydrolyse de l'ATP. Une protéase couplée à une ligase interviendrait également. Les spermatozoïdes subissent une altération structurale lors de l'émission dam l'eau douce qui ne se produit pas dans la solution saline d'activation; cependant, dans les deux cas, la mobilité des spermatozoïdes est brève, 30sec. chez la truite et une minute chez la carpe. Leur trajectoire est circulaire; la fréquence des battements flagellaires, élevée lors du déclenchement de la mobilité (50–60 Hz), décroît ensuite jusqu'à 10–20 Hz: on constate alors l'arrêt du déplacement des têtes spermatiques bien que les flagelles des sermatozoïdes de carpe continuent leurs battements à une fréquence faible (<10 Hz). La vitesse de déplacement diminue parallèlement à la fréquence et la distance moyenne parcourue est de 3 mm chez la truite et 5 mm chez la carpe. La mobilité des spermatozoïdes de truite et de carpe est influencée par l'environnement ionique. Une forte concentration en ion K+chez la truite et une pression osmotique élevée chez la carpe, inhibent la mobilité. D'autres ions tels que H+Ca2+Mg2+interviennent également dans la régulation du mouvement. Lors de l'initiation du mouvement des spermatozoïdes de truite, I'activité de l'adénylate cyclase et la concentration en AMPc augmentent. L'AMPc serait donc un facteur du déclenchement de la mobilité, il entraînerait la phosphorylation d'une protéine 15 Kd par l'intermédiaire d'une Tyrosine protéine kinase et interviendrait aussiin vivodans l'acquisition de la mobilité. Lorsque les spermatozoïdes de carpe ne sont pas mobiles dans la solution d'activation, ils peuvent subir une “maturationin vitro”par incubation dans un milieu riche en potassium et de pression osmotique élevée. Aprés l' initiation du mouvement dans une solution d'activation, la quantité d'ATP diminue raidement dans les deux espèces. L'ATP se régénère spontanément dans les uinze minutes qui suivent l' arrêt du mouvement chez la truite. Chez la carpe il n'y a pas de restauration de l'ATP dans la solution saline d'activation mais elle est possible en replasant les spermatozoïdes en condition d'immo‐bilisation (forte pression osmotique). II a été montré que des spermatozoides de truite démembranés sont réactivables en présence d'ATPMg2+et d' AMPc, alors que chez la carpe l'AMPc n'est pas néces‐saire.SummarySpermatozoa motility of trout(Oncorhynchus mykiss)and carp(Cyprinus carpio)In the past fifteen years, teleost spermatozoa and seminal plasma were studied with the aim of understanding the mechanical and chemical processes which regulate motility. Trout and carp spermatozoa were particularly studied; their flaella are classic, with “9+2” microtubule doublets and outer and inner associated dynein arms. Flagellar beating results from hooking/unhooking cycles from the dynein arms of one microtubule to the one adjacent through ATP hydrolysis. A protease coupled to a ligase is probably also involved. Spermatozoa undergo drastic structural change when shed in freshwater but not in an activating saline solution; however, in both cases, motility is short, 30 sec. in trout and one minute in carp. Trajectories are circular; flagellar beat frequencies are high at the beginning of the motility (50–60Hz), and decrease to 10–20Hz: one observes that sperm head stop, whereas flagella of carp spermatozoa continue beating at low frequency (<10 Hz). The velocity decreases with frequency; the mean duration of displacement is 3 mm in trout and 5 mm in carp. Trout and carp spermatozoa motility are influenced by the ionic external environment. A high concentration of K+ions in trout and a high osmotic pressure in carp inhibit motility. Other ions like H+Ca2+Mg2+also interfere with the motility regulation. At the time of trout spermatozoa movement initiation, adenylate cyclase activit and cAMP concentration increase. cAMP is likely a factor involved in the initiation of motility, which may also involve the phosphorylation of a protein 15 Kd through a Tyrosine protein kinase activity. cAMP may also be involved in the acquisition of sperm motilityin vivoWhen carp spermatozoa are immotile in the activating solution, they can undergo a “maturationin vitro”(i.e. the acquisition of the capacity to move) by incubation in a medium with high concentration of K+and with a high osmotic pressure (400 m Osm/kg). After initiation of movement in the activating solution, intracellular ATP decreases rapidly in the spermatozoa of the two species. ATP regeneration occurs spontaneously within fifteen minutes following the arrest of movement in trout. In carp there is no ATP regeneration in activating saline solution, but replacing sermatozoa in an immobilizing solution (high osmotic pressure) results in a recovery of the intracellular ATP content. It was shown that

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1993.tb00389.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryThe sagittal otolith ofMacruronus novaezelandiae(Merlucciidae; Teleostei) showed cycles of strontium, calcium, nitrogen, carbon and oxygen in proton microprobe traces along both the sulcal to anti‐sulcal growth axis, and the dorso‐ventral rowth axis of the otolith. The cycles of strontium in the dorso‐ventral growth axis had peak‐to‐peai distances similar to those of annual peaks expected from daily microincrement estimat

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1993.tb00390.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryVariation in the proportions of serum esterase genetic polymorhisms drawn from samples of skipjack tuna (Katsuwonus elamis) has been used to identify geneticaty isolated stocks ofK. pelamisin the South Pacific, based on the assumptions that variation in serum esterase gene proportion was essentially stochastic; such aruments are shown to be unacceptable. There is evidence that serum esterases may be involved in the deknsive resonses of vertebrates to parasites, and that genetic variation at a number of loci may be related to growth rate. It can be shown in a large proportion of samples that serum esterase gene proportion inK. pelamiswas correlated to measures of growth rate. This implies that the Pacific‐wide variation in esterase proportions in skipjack tuna may be due to local selection gradients involving growth rat

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1993.tb00391.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryAn investigation of catches of 12 commercial fish species and species groups from the Nigerian inshore trawl fishery between 1971 and 1987, indicated that total catch‐per‐unit effort (CPUE) of all species was less variable among these years than the CPUE of most individual species or species grous Some possible causes for the large fluctuations in the abundances of the single species or groups are Jsius

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1993.tb00392.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryOocyte growth within the follicle is due to the accumulation of the normal cytoplasmic components, and the endocytosis of hepatic derived rotein, the vitellogenins. Vitellogenesis started in 200μm oocytes; during oocyte growth the olk Lbules increased in number and size. Yolk globule morphology varies durin oocyte growth: irst Jey appear uniform and dense; then, in 500 μm oocytes they oten appear to be divided into 2 or 3 dense masses. Yolk proteins of pre‐maturational oocytes at different stages were compared with those of ovulated eggs by SDS gel electrophoresis. The largest comonents stained by Coomassie blue and those stained by Stains‐all, which had formed during viteligenesis, either disappeared or diminished, while smaller components appeared. The changes in yolk rotein banding patterns during oocyte maturation are suggestive of extensive secondary proteol sis of yolk proteins; such secondary proteolysis may generate, as in other marine teleosts, part of the osmotic gradient associated with the resumption of oocyte meiotic maturation, before ovul

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1993.tb00393.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryThe Mahakam River floodplain fishery was studied between 1979 and 1990. With annual catches of 15,000–35,000 t (metric tonnes), it is one of the most productive freshwater artisanal fisheries in Indonesia. Landings are dominated by one crustacean and 15 fish species, of which five make u more than two‐thirds by weight. A negative relationship between landed weight and price was obtaineB for 19 of 24 fisheries products. Average catch rates were determined for 14 gear pes The most efficient active gear were handlines, liftnets and castnets (average 1629–4296 g. gear‐1. houi‐1). The best passive gear types were vertical slittraps and gillnets (average 1042–1160 g gear‐1day‐1). Gear ownership type changed significantly betwee

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1993.tb00394.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryIn 1987 there were 18,800 households on the Mahakam floodplain. Of these, 5,800 were full‐time and 6,200 arttime fishermen, with the remainder full‐time farmers. Daily and seasonal catch levels were variabfe aid related to water level changes. Catches raned between 1.84 and 5.7t person‐1year‐1for full‐time and between 0.97 and 1.6 t person‐1year‐1for part‐time fishermen. Earnings per person from fishing averaged respectively R. 1,400,000 and Rp. 400,000 in 1987, comprising 75–95% and 33–85 % of their total income. Overall labour input per person was 287 days year‐1and 5.04 hours day‐1for full‐time and 250–265 days year‐1and 5.12 hours day‐1for part‐time fishermen. The proportions that came from fishery‐related activities were resectively 25–60 % and 10–25 %. Labour requirements to clean, salt and dry one kilogram o

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1993.tb00395.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryThe fishery on the Mahakam River floodplain is important and therefore heavily exploited. Mesh sizes of gillnets and beach seines have decreased rapidly in recent times, indicating that overexploitation may soon become a roblem; biological data support this. Actual and estimated yields, calculated using standard methods, are compared and the relationship of total catch to water levels determined. Annual catches were most significantly related to the number of days when water levels were>9.2 m above mean sea level (AMSL) in the twelve‐month period beginning in May of the year previous to the catch. The relationship took the form Y = 9476.105 + 115.5967X (r = 0.92), where Y is the catch in t (metric tonnes) and X the number of days when water levels were>9.2 m. The consequences for future management policies are discusse

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1993.tb00396.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryThe total lengths and numbers ofCnidoglanis macrocephaluscaught in the closed and open fishing waters of Wilson Inlet, using a gill net cornrising a wide range of mesh sizes, were recorded. These data were then compared with those obtained for the commercial fishery. The results strongly indicate that (I) the density and percentage contribution of large fish are lower in open than in closed fishing waters, (II) female fish were more readily caught than male fish and (III) the minimum legal mesh size and minimum legal length for C.macrocephalusshould be increased to prevent fish being caught before they reach sexual maturity.

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1993.tb00397.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryTwaire,Alosa fallax lacustris, is the basic ingredient of a typical iscine product locally called “missol‐tini”, prepared on the shores of Lake Corno. The artisan technokgy provides an optimal hygienic and nutritional product. When preserved, there is a total absence of contaminating microorganisms; lac‐tobacilli and halophilous represent harmless bacteria. The food value lies in the high protein content with a notable lipid presence, plus the significant presence of polyunsaturated fatty acids. These attributes make “missoltini” a complementary component in any fish‐based diet, such diets having long been recognized as valid in the prevention of cardiovas

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1993.tb00398.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY