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1.
The initial appearance and the development of Leydig cells (LCs), the sites of steroid hormone production in the testis, were investigated ultrastructurally during testicular differentiation in the Japanese eel, Anguilla japonica. In addition, the effects of a single injection of human chorionic gonadotropin (HCG; 5 IU g body weight-1) on histological changes of the testes and serum 11-ketotestosterone (11-KT) were examined at various stages (15–18, 20–23, 26–29, 32–35, 38–41 and 46–50 cm body length (BL)) of testicular differentiation. Testicular differentiation was morphologically characterized by the development of loose connective tissue on the medial side in animals 18–29 cm in BL. Ultrastructurally, LCs were first identified in the loose connective tissue of the testis of the 23 cm fish. In the testes of fish over 32 cm, clusters of LCs were distributed throughout the interstitial region accompanying the increase in number of spermatogonia. In fish larger than 32 cm, spermatogenesis was induced by administration of HCG; serum 11-KT levels were also raised. On the other hand, there was no effect on spermatogenesis or serum 11-KT levels in fish less than 29 cm, or in the controls. These result suggests that morphological differentiation of LCs occurs in testis of the 23 cm eel, and subsequently, the testes of eels of BL more than 32 cm acquire the capability to produce steroid hormones. 相似文献
2.
S. Miura T. Komatsu M. Higa R.K. Bhandari S. Nakamura M. Nakamura 《Fish physiology and biochemistry》2003,28(1-4):165-166
To clarify the process of sex differentiation in protandrous anemone fish, histological structure of their gonads was examined from 1 day to 214 days after hatching (dah). Gonadal development was first characterized by differentiation of ovarian tissues at 61 dah, followed by interspersed appearance of testicular tissues in the ovary at 214 dah. 相似文献
3.
4.
Long-chain polyunsaturated fatty acids (LCPUFA) with 20 or 22 carbons are considered important to the development of infants
and sometimes added to infant formulae. In this study, two characteristic sources of n-3 LCPUFA (fish oil and microalgal oil)
were orally administrated to rat pups of mildly n-3 PUFA — deficient dams to compare the consequences of the administration.
The milk from the dams fed a n-3 PUFA — restricted diet contained less n-3 LCPUFA than that of the dams fed a control diet.
Pups were administered 1 mg/g weight of the test oil at the age of 5–7 days. At the age of 7 days, they were sacrificed before
or after the administration and fatty acid compositions of the stomach and serum lipid were studied. The administration changed
docosahexaenoic acid (DHA; 22:6n−3) levels in the stomach contents and serum lipids with time. Eicosapentaenoic acid (EPA;
20:5n−3) levels increased immediately after the administration of fish oil. The administration of microalgal oil also affected
the serum lipid EPA level, in spite of a lack of EPA. In this study, both oils effectively supplemented DHA. Fish oil returned
the serum EPA level close to the control value while microalgae oil had little effect. 相似文献
5.
Youji Wang Menghong Hu Weimin Wang Ling Cao Yi Yang Biping Lü Rongrong Yao 《Aquaculture International》2008,16(6):539-549
The diel feeding rhythm and ontogenesis during early life stage of loach Misgurnus anguillicaudatus were investigated under experimental conditions (light: L 06:00–18:00, D 18:00–06:00 h). Morphological and behavioral developments
of loach from newly hatched to 40 days after hatching were observed. Larvae were able to prey on daphnia 3–4 days after hatching
at 23 ± 0.5°C. As the larvae grew, they showed an increasing feeding capacity and a distinct feeding rhythm. Feeding intensity
and incidence for day-4 larvae were highest at 10:00 and 16:00 h. The highest levels of feeding intensity for day-12 larvae
occurred at 08:00, 12:00, and 18:00 h as did feeding incidence. By day 20, when the larvae metamorphosed, the highest levels
of feeding intensity occurred at 06:00, 18:00, and 24:00 h and were concurrent with the highest feeding incidence. After metamorphosis,
feeding capacity had again increased considerably and, in contrast to the earlier stages before day 20, feeding intensity
for day-30 juveniles peaked at 05:00 and 20:00 h, about 1–2 h after the maximum feeding incidence. The feeding rhythm of loach
juveniles at day 40 was almost the same as the day-30 juveniles. The estimated maximum daily feeding rates were 43.1%, 33.4%,
19.0%, 12.8%, and 5.8% of body weight on days 4, 12, 20, 30, and 40, respectively. Thus, loach was found to have different
feeding rhythms in the pre- and post-metamorphosis stages, with the highest feeding activity in daytime during the larval
planktonic stage before metamorphosis, and intensely nocturnal feeding behavior during the juvenile benthic stage after metamorphosis. 相似文献
6.
Tsuyoshi Ogasawara Tetsuya Hirano Toshio Akiyama Shigeru Arai Masatomo Tagawa 《Fish physiology and biochemistry》1989,7(1-6):309-313
Freshwater adaptability of chum salmon was examined in juvenile fish reared in seawater for 4 months. The fish, weighing about
40g, were transferred directly to fresh water in October, when their cohorts are migrating in the North Pacific Ocean. Plasma
sodium concentration decreased from 167 mM in seawater to about 130 mM during the first 24h, and increased gradually during
2–7 days after the transfer. No immunoreactive prolactin (PRL) was detected in the plasma of the seawater-adapted fish nor
during the first 24h in fresh water. Significant levels of PRL were detected after 2–3 days. The maximal level (2.6 ng/ml)
was observed after 5 days and became undetectable again after 7 days; no significant correlation was seen between the changes
in plasma sodium and PRL levels during the transfer. Plasma growth hormone levels were relatively constant, except for a significant
decrease 12h after the transfer. Although plasma thyroxine levels were highly variable during the experiment, a significant
decrease and an increase were observed 12h and 5 days after the transfer, respectively. The present study indicates that juvenile
chum salmon retain hyperosmoregulatory ability even after prolonged rearing in seawater. Examination of turnover rates, rather
than changes in plasma levels, seems to be essential to clarify the osmoregulatory roles of the hormones. 相似文献
7.
Marcelino Herrera Ismael Hachero-Cruzado Catarina Oliveira José F. Ferrer José M. Márquez Montserrat Rosano Jose I. Navas 《Aquaculture International》2010,18(3):475-485
The weaning phase can be decisive in fish-culture viability. In this work, the relationship between the initial size and weaning
success has been studied in wedge sole (Dicologoglossa cuneata). For each age (30, 50, and 70 days after hatching, DAH), two to three sizes were selected, and all were put on the same
feeding schedule for 20 days. Each batch (three replicates) was sampled at 1, 10, and 20 days. Specific growth rate (SGR)
and survival were compared at the end of the co-feeding period, after 10 days on dry feed only. The best results for survival
and growth were found with the smallest larvae, and vice versa. The SGRs and survival rates recorded during the co-feeding
period were higher (0.8–15.6 day−1 and 68.3–97.8%) than those from the dry-food phase (0.9–4.7 day−1 and 56.3–66.7%). Successful weaning (survival = 65% and SGR = 9.3 day−1) is possible with 30 DAH larvae (7.6–8.1 mm and 3.9–4.6 mg). In conclusion, the most effective weaning would be possible
at 30 DAH, implying significant Artemia savings (25–50%). 相似文献
8.
Fırat O Cogun HY Yüzereroğlu TA Gök G Fırat O Kargin F Kötemen Y 《Fish physiology and biochemistry》2011,37(3):657-666
The present study was designed to compare the responses in freshwater fish Oreochromis niloticus exposed to a synthetic pyrethroid, cypermethrin (CYP); an essential metal, copper (Cu); and a nonessential metal, lead (Pb).
Fish were exposed to 0.05 μg/l CYP, 0.05 mg/l Cu, and 0.05 mg/l Pb for 4 and 21 days, and the alterations in serum enzyme
activities, metabolite, and ion levels were determined. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST)
activities increased in response to CYP, Cu, and Pb exposures at both exposure periods. While elevations in alkaline phosphatase
(ALP) and lactate dehydrogenase (LDH) activities and in cholesterol level were observed in pesticide-exposed fish at 4 and
21 days, they increased in Cu- and Pb-exposed fish at 21 days. Although metal-exposed fish showed increases in cortisol and
glucose levels at 4 days followed by a return to control levels at the end of the exposure period, their levels elevated in
pesticide-exposed fish at both exposure periods. Total protein levels decreased in Pb- and pesticide-exposed fish at 21 days.
Na+ and Cl− levels decreased in pesticide-exposed fish at both exposure periods and in Cu- and Pb-exposed fish at 21 days. The exposures
of pesticide and metals caused an elevation in K+ level at the end of the exposure period. The present study showed that observed alterations in all serum biochemical parameters
of fish-treated pesticide were higher than those in fish exposed to metals. 相似文献
9.
Michiya Matsuyama Shinji Adachi Yoshitaka Nagahama Katsuhiko Maruyama Shuhei Matsura 《Fish physiology and biochemistry》1990,8(4):329-338
Ovarian developmental stages and serum steroid hormone levels were examined at six different times of day (0100, 0600, 1000,
1300, 1600, 2000 h) in a marine teleost, the Japanese whiting Sillago japonica, which has an asynchronous-type ovary containing oocytes at various stages of development and spawns every day during a period
ranging up to three months. The largest oocytes in the ovaries at the active vitellogenic or post-vitellogenic stages were
found between 0100 and 1300 h. Oocyte maturation indicated by germinal vesicle breakdown (GVBD) occurred at 1600 h, and ovulated
oocytes were observed in the ovaries collected at 2000 h. These processes were accompanied by a significant daily change in
serum steroid hormone levels. The serum level of estradiol-17β showed a peak in fish with mature oocytes sampled at 1600 h.
In these fish, the second-largest oocytes in the ovaries were at the initial stage of vigorous vitellogenesis, the secondary
yolk stage. Therefore the highest level of serum estradiol-17β was considered to be due to the second-largest oocytes. Testosterone
levels remained low and constant throughout the experimental period. The serum levels of 17α,20β-dihydroxy-4-pregnen-3-one
(17α,20β-diOHprog) peaked at 1600 h at which time all fish had mature oocytes. These results indicate that the Japanese whiting
possesses a diurnal rhythm of oocyte development including vitellogenesis, oocyte maturation and ovulation, and further suggest
that daily cycles in oocyte growth and maturation which simultaneously take place in an ovary are regulated by diurnal secretions
of estradiol-17β and the maturation-inducing steroid, 17α,20β-diOHprog. 相似文献
10.
Uscanga-Martínez A Perales-García N Alvarez-González CA Moyano FJ Tovar-Ramírez D Gisbert GE Márquez-Couturier G Contreras-Sánchez WM Arias-Rodríguez L Indy JR 《Fish physiology and biochemistry》2011,37(3):667-680
Several samples of P. splendida larvae were obtained from eggs until day 60 after hatching (dah) to determine acid and alkaline proteases, trypsin, chymotrypsin,
leucine aminopeptidase, α-amylase, lipase, and acid and alkaline phosphatase activities using biochemical techniques. Additionally,
SDS–PAGE alkaline protease zymogram and PAGE acid protease zymogram were carried out to identify active isoforms during larviculture.
Alkaline protease and chymotrypsin were present at the moment of hatching, increased gradually reaching the maximum values
at 35 dah. Trypsin and leucine aminopeptidase activities were low from hatching, increasing gradually as larvae grew. Alkaline
protease zymogram showed four zymogens, which appears at different days, remaining present until the end of the larviculture
(95.2 kDa at 11 dah, 26.4 kDa at 9 dah, 21.4 kDa at 3 dah, and 23.3 kDa at hatching). Pepsin activity was present at day 7
after hatching and increased progressively until the end of the larviculture. Acid protease zymogram only showed one zymogen
(0.65 rf), which appear at 6 dah. Lipase was high at the time of hatching and increased until 15 dah, after which decreased
gradually. Amylase was high from the beginning and until 15 dah and then decreased rapidly to almost nothing onward. Alkaline
and acid phosphatases presented a high activity at the egg stage, fell slightly during the first feeding and increased again
from 20 to 30 dah. Results obtained in this study show that larvae can be fed artificial diets starting on day 10 after hatching. 相似文献
11.
EWA KAMLER LESZEK MYSZKOWSKI RAFAŁ KAMIŃSKI MICHAŁ KORWIN-KOSSAKOWSKI JACEK WOLNICKI 《Aquaculture International》2006,14(1-2):99-111
Duplicate groups of tench (Tinca tinca) juveniles (mean weight 0.69 g) were fed at 28 °C for 70 days either a commercial formulated diet, Futura, or frozen Chironomidae
larvae at four levels: below satiation, at about satiation, above satiation and well above satiation. These are represented
by the feeding groups F1–F4 and C1–C4, respectively. No mortality was observed throughout the experiment. In groups F2–F4
a considerable incidence of uneaten food (>40% observations), deformities of the caudal penduncle, retarded growth, elevated
condition coefficient (>1.2), reduced amounts of minerals in the tissue (<10% dry matter), high C/N ratio (>5) and high caloric
value of the tissue (>28 J mg−1 dry matter) (the latter two suggesting excessive fat deposits), were found. The combination of these indices was indicative
of overfeeding in fish fed the Futura diet at the daily doses ≥2.7% fish biomass. First symptoms of overfeeding: a considerable
incidence of uneaten food, retarded growth, and elevated C/N ratio were observed in the group fed Chironomidae larvae at the
highest level, (C4, wet Chironomidae 20.7% of the fish biomass daily, that is, 3.9% of dry chironomids per fish biomass and
day). Thus, restricted daily doses of formulated diet not exceeding 2.5% fish biomass are recommended for tench juveniles
aged 130–200 days post hatch. Safe daily doses of frozen Chironomidae (in terms of larvae dry weight) remain below 3.5% of
fish biomass. 相似文献
12.
P. Silva D. M. Power L. M. P. Valente N. Silva R. A. F. Monteiro E. Rocha 《Fish physiology and biochemistry》2010,36(4):1125-1132
Previous studies on the histochemistry and immunoreactivity of fibres in lateral muscle of blackspot seabream indicated that
there is a developmental transition in the composition of myofibrillar proteins, which presumably reflects changes in contractile
function as the fish grows. We hypothesize that the phenomenon underscores age and spatial differences in the expression of
myosin light chains (MLC), not studied yet in this species. In this study, we examined selected stages in the post-hatching
development of the muscle of blackspot seabream: hatching (0 days), mouth opening (5 days), weaning (40 days) and juveniles
(70 days). The spatial expression of embryonic MLC 1 (MLC1), 2 (MLC2) and 3 (MLC3) was studied by in situ hybridization. Overall,
MLC expression patterns were overlapping and restricted to the fast muscle. At hatching and mouth opening, all MLC types were
highly expressed throughout the musculature in fast muscle. The expression levels in fast muscle remained high until weaning
when germinal zones appeared on the dorsal and ventral areas. The germinal zones were characterized by small-diameter fast
fibres with high levels of MLC expression. This pattern persisted up to day 70, when the germinal zones disappeared and expression
of MLCs was observed only in the smaller cells of the fast muscle mosaic. These results support our hypothesis and, together
with previous imuno- and histochemistry results, allow a better understanding of the mechanism of muscle differentiation and
growth in fish beyond larval stages, and form- the basis for further comparative and experimental studies with this economically
relevant species. 相似文献
13.
Prasad M Kumar A Mishra D Srivastav SK Srivastav AK 《Fish physiology and biochemistry》2011,37(3):505-510
The present study aimed at investigating the effects of Nerium indicum leaf extract on the blood electrolytes of Heteropneustes fossilis for short- and long term. Fish were subjected to Nerium
indicum leaf extract for short term (11.27 mg/L i.e. 0.8 of 96 h LC50) and long term (2.81 mg/L i.e. 0.2 of 96 h LC50). Fish were killed on each time intervals from control and experimental (Nerium
indicum) groups after 24, 48, 72, and 96 h in short-term exposure and after 7, 14, 21, and 28 days in long-term experiment. Blood
samples were analyzed for calcium and inorganic phosphate levels. Acute exposure of Nerium
indicum leaf extract caused a progressive decrease in the serum calcium levels after 48 h in fish H. fossilis, which persists till the close of the experiment (96 h). The serum inorganic phosphate levels remain unaffected till 48 h
in the Nerium
indicum leaf extract–exposed fish. After 72 and 96 h, the levels exhibit a decrease. Chronic Nerium
indicum leaf extract treatment provoked a decrease in serum calcium levels at day 14. This decrease continues till 28 days. The serum
phosphate level of the Nerium
indicum leaf extract–treated fish decreases on day 14 and 21. However, on day 28, the levels become close to the normal values. We
conclude that Nerium indicum leaf extract exposure alters the blood electrolytes of the fish, thus causing physiological disturbances which might affect
seriously the normal vital functions, growth rate, reproduction, and their survival in nature. 相似文献
14.
The present study provides information on the histomorphological development of digestive system of discus, Symphyosodon spp., larvae during the first month of life. Discus larvae are altricial at hatching, with an undifferentiated digestive
tract and a large yolksac, which is completely consumed within 7 days. The mouth opens 3 days after hatching (DAH) and the
larvae starts feeding on AF Artemia at 4 DAH when offered. At 3 DAH the digestive tract is differentiated with distinct esophagus, stomach anlage, and mid- and
hindguts. At 5 DAH, discus larvae is an active feeder, equipped with partly developed jaws and ossified gill arches and an
inflated swim bladder. The liver and pancreas are present and supranuclear inclusion vacuoles (SIV) appear in the hindgut
for the first time. Gastric glands in stomach were first observed 7 DAH and proliferated by 11–13 DAH. SIV were a common feature
in the midgut and hindgut epithelium until 15–23 DAH. Therefore, exclusive use of artificial diets should be postponed until
2–3 weeks after hatching. 相似文献
15.
Changes in Ca2+ content and flux, and the development of skin chloride cells in embryos and larvae of tilapia, Oreochromis mossambicus, were studied. Tilapia embryos hatched within 96h at an ambient temperature of 26–28°C. Total body Ca2+ content was maintained at a constant level, about 4–8 nmol per individual, during embryonic development. However, a rapid
increase in body Ca2+ level was observed after hatching, 12.8 to 575.3 nmol per individual from day 1 to day 10 after hatching. A significant influx
and efflux of Ca2+ occurred during development, with the average influx rate for Ca2+ increasing from 5.9 pmol mg−1 h−1 at 48h postfertilization to 47.8 pmol mg−1 h−1 at 1 day posthatching. The skin was proposed as the main site for Ca2+ influx before the development of gills, and the increased Ca2+ influx may be ascribed to gradual differentiation of skin surface and chloride cells during embryonic development. Ca2+ efflux was 16–56 pmol mg−1 h−1 in 1-day-old larvae. The resulting net influx of Ca2+, 10–12 pmol mg−1 h−1, accounted for the increased Ca2+ content after hatching. When comparing the measured and estimated ratios of efflux and influx, active transport was suggested
to be involved in the uptake of Ca2+. Chloride cells, which may be responsible for the active uptake of Ca2+, started to differentiate in the skin of embryos 48h after fertilization, and the density of chloride cells increased following
the development. A possibility of active transport for Ca2+ in early developmental stages of tilapia is suggested. 相似文献
16.
Mohsen Abdel-Tawwab 《Aquaculture International》2012,20(2):317-331
Yeasts used as a probiotic in fish diets could stimulate fish resistance against bacterial infection and could enhance the
activities of digestive enzymes in fish guts. In addition to yeast importance, dietary protein is another important part in
fish diets that should be carefully optimized to meet fish requirement. It is proposed that the yeast supplementation may
enhance the dietary protein turnover and reduce the protein requirement for fish. Therefore, the interactive effects of dietary
protein and yeast levels on the growth performance of Nile tilapia, Oreochromis niloticus (L.) fry and their challenge against Aeromonas hydrophila infection was evaluated. In the present study, ten experimental diets were formulated to contain either 35% or 45% crude
protein (CP). For each protein level treatment, bakery yeast (Saccharomyces cerevisiae) was supplemented at 0.0, 0.50, 1.0, 2.0, or 5.0 g/kg diet. Fish (0.25–0.48 g) were distributed at a rate of 25 fish per
140-L aquarium. For each diet, triplicate aquaria were fed twice a day, 5 days a week for 12 weeks. Fish growth and feed utilization
were significantly affected by either dietary protein or yeast levels alone, while no significant effect of their interaction
was observed. The highest fish growth was obtained at 1.0–5.0 g yeast/kg diet at both protein levels; however, the fish performance
at 45% CP was better than that fed on 35% CP diets. The optimum feed conversion ratio (FCR) was obtained when fish fed on
1.0–5.0 and 2.0–5.0 g yeast/kg diet at 35 and 45% CP, respectively. The cumulative fish mortality, after interperitoneal injection
with A. hydrophila for 10 days, and bactericidal activity was significantly higher in fish fed 35% CP diets than those fed 45% CP diets. Both
variables decreased significantly with the increase in yeast levels. The lowest bacterial count and bactericidal activity
were obtained in fish fed 5.0 g yeast/kg diet irrespective to dietary protein levels. It could be concluded that the inclusion
of live bakery yeast in practical diets could improve the growth performances, feed utilization, and physiological status
of Nile tilapia fry and their challenge against A. hydrophila infection. Moreover, fish performance when fed 45% CP diet was better than those fed 35% CP diet. Based on these results,
the most suitable yeast level for maximum Nile tilapia growth was determined to be 2.0 g yeast/kg diet with 45% CP diet; however,
this level was recommended to stimulate their productive performance and enhances their resistance against A. hydrophila infection. 相似文献
17.
采用放射免疫分析测定法(RIA)对人工繁殖的中华鲟(Acipenser sinensis)早期发育阶段中17β-雌二醇(17β-estradiol,E2)和睾酮(testosterone,T)的整体水平进行了测定。实验共测定了4批次(分别来自4尾雌鲟)受精卵及仔鱼的E2和T水平,结果表明:中华鲟胚胎发育期间E2水平在小范围内波动,T水平除胚胎发育早期出现上升外总体呈下降趋势;仔鱼出膜后E2水平开始逐渐上升,T水平是先降低后又逐渐升高。其中第1批次的测定结果(单位为pg/gtissue)为:胚胎发育期间E2水平在1.37~7.38之间波动,仔鱼出膜后3d为5.21,出膜后9d为37.26;胚胎发育期间T水平最低为293.58,最高为1420.41,仔鱼出膜后4d为117.96,出膜后7d为27.25,出膜后9d为148.48。对于仔鱼出膜后体内高水平的E2和T的来源,推测其可能与仔鱼自身合成性类固醇激素有关。另外,本实验中还发现,质量较差的卵子T水平明显低于质量较好者。 相似文献
18.
Fui Fui Ching Norazmi Othman Azaharie Anuar Rossita Shapawi Shigeharu Senoo 《International Aquatic Research》2018,10(4):391-402
This study aims to reveal the first report of the natural spawning of F1 hybrid grouper (TGGG), a crossbreed between the tiger grouper, Epinephelus fuscoguttatus × giant grouper, E. lanceolatus, since its first production in 2006. This marks the completion of its full cycle after a 10-year period. In order to establish a seed rearing protocol for a novel F2 hybrid TGGG, natural spawning, embryonic and larval developments were thoroughly observed. Five batches of natural spawning were recorded with an average of 1.50–15.3 kg eggs collected, while fertilization and hatching rates were recorded at 85.3–97.6%, and 63.0–98.3%, respectively. F2 larvae hatched out at 17:50 hours with an average body size of 1.74 ± 0.01 mm, and a yolk sac volume of 0.85 ± 0.197 mm3. The first feeding was initiated 3 days after hatching, which coincided with the onset of functional feeding apparatus and active swimming behavior. Larval dorsal and pelvic spines were formed at 6 days AH coupled with dynamic feeding activity, as more food was found in the digestive tract. Meanwhile, the F2 hybrid grouper shifted habitat from pelagic to benthic as early as 25 days AH, and entered a juvenile stage at 35 days AH, attaining a skin coloration similar to that of the F1 juvenile. This study concluded that naturally spawned eggs of F2 hybrid TGGG were exceptionally high in quality, although larvae were small and fragile, and performed vigorous feeding activities and cannibalistic behavior. Thus, these findings can serve as primary data to further develop the optimal rearing protocol to enhance the overall rearing performance. 相似文献
19.
Youichi Hayakawa Hidekazu Nagaya Hiroki Kaki Komei Hotta Makito Kobayashi 《Fisheries Science》2009,75(1):137-144
We previously demonstrated the biological activities of single-chain recombinant gonadotropins (scGTHs) of goldfish Carrassius auratus follicle-stimulating hormone (scFSH) and luteinizing hormone (scLH), produced by a baculovirus–silkworm larvae system, by
using in vivo bioassays with some fishes including Japanese eel Anguilla japonica. Among the bioassays, we succeeded in induction of spermatogenesis of sexually immature male Japanese eels by both scFSH
and scLH, especially resulting in the occurrence of spermatozoa in scLH-administered males. However, those recombinant hormones
did not induce enlargement of testes. In order to further confirm the potency of recombinant GTHs for use in aquaculture species,
we administered scFSH and scLH to males of Japanese eel at higher dosage and frequency (eight times with 2–5 days interval)
than those of the previous study (five or six times with 7 days intervals), including combination of scFSH and scLH administration
(scFSH–scLH). Gonadosomatic indices (GSI) of scLH- and scFSH–scLH-administered males were larger than those of initial control
males and of control males that were injected with saline. Enlargement of testes was also confirmed by measurement of testicular
lobe size in scFSH-, scLH-, and scFSH–scLH-administered males. By histological observation, occurrence of spermatozoa was
confirmed in scLH- and scFSH–scLH-administered eels. Although milt production was not induced, higher dosage and frequency
of scGTH administration was effective in promoting testicular development of immature eels. Thus, single-chain fish GTHs produced
by the baculovirus–silkworm larvae system could be a useful tool for promotion of gonadal maturation in aquaculture fishes. 相似文献
20.
The aim of the present study was to investigate concentrations of total mercury (THg) and methylmercury (MeHG) in the common
carp from Czech ponds of Rožmberk, Spolsky, Nezmar, and Velky Bědny. Seven common carps (Cyprinus
caprio) from each of the ponds were caught. Muscle tissue, the liver, and the soft and hard roe were used for the tests. Total mercury
and methylmercury were found in all the muscle tissue samples examined. Detection limits for total mercury and methylmercury
determination methods were 0.001 mg kg–1 and 0.013 mg kg−1 respectively. Methylmercury levels in the liver and gonads were below the method’s limits of detection. THg and MeHg concentrations
in muscle tissues were 0.018–0.063 mg kg–1 w.w. and 0.019–0.063 mg kg–1 w.w. respectively. MeHg made up 90–100% of THg in muscle tissues. Total mercury and methylmercury concentrations were significantly
(P < 0.05) higher in fish from the Spolsky pond than from the Nezmar pond. MeHg/THg ratios were significantly (P < 0.05) higher in fish from the Rožmberk, Spolsky and Nezmar ponds compared with fish from the Velky Bědny pond. 相似文献