Incorporation of brewery waste in supplementary feed and its impact on growth in some carps

Brewery waste (brewer's grains) was used at four different levels (10%, 20%, 30% and 40% w/w) replacing rice bran in fish diet under a semi-intensive culture system and its impact on the growth of catla, Catla catla; rohu, Labeo rohita and mrigal, Cirrhina mrigala, was studied. Growth in terms of body weight gain was maximum in C. catla and L. rohita fed on a diet containing 30% brewery waste in the feed, whereas C. mrigala, fed on a diet containing brewery waste at the above mentioned levels showed poorer growth than the control. A better growth performance was attributed to better absorption and utilization ability.     

Oocyte maturation in Clarias batrachus: in vitro effect of various gonadotropins and homologous pituitary homogenate.

The effects of five different gonadotropins and homologous pituitary homogenate (HP) on germinal vesicle breakdown (GVBD) were investigated in vitro using folliculated oocytes of Clarias batrachus. Among all the gonadotropins, salmon gonadotropin (SG-G100) was the most potent in vitro inducer of oocyte maturation. At concentrations of 1, 0.1, 0.01 and 0.001 microgram/ml it induced 86.98 +/- 2.71, 68.74 +/- 2.85, 44.56 +/- 1.75 and 25.90 +/- 2.36% GVBD. Next to SG-G100 in inducing GVBD was luteinizing hormone (LH) which was consistently found to be effective at all the concentrations used. Human chorionic gonadotropin was also found to be effective at all the concentrations but when compared to SG-G100 and LH, it was less effective. Follicle stimulating hormone and pregnant mare serum gonadotropin were found to be effective at higher concentrations but were ineffective at the lowest concentration. HP treatment resulted in a significant number of GVBD at all the three concentrations used.     

Bioactive forms of gonadotropin releasing hormone in the brain of an Indian major carp,Catla catla (Ham.)

Two forms of biologically active gonadotropin releasing hormones were isolated from the hypothalami ofCatla catla. Gonadotropin releasing hormone activity was studiedin vitro using enzymatically dispersed carp pituitary cell incubation system. Gonadotropin released into the medium was measured by carp gonadotropin-radio immuno assay. Acetic acid extracted hypothalamic material was subjected to acetone fractionation. Among the three protein pellets obtained at different time periods (ACI, ACII and ACIII), AC II exhibited the gonadotropin releasing hormone activity. Gel filtration of AC II through Sephadex G-25 column showed three protein peaks (SG I, SG II SGIII) and only S G II demonstrated strong gonadotropin releasing hormone activity. Elution of SG II through FPLC Mono Q column (an anion exchanger) in NaCl gradient programme showed one unadsorbed (MQ I) and three adsorbed (MQ II, MQ III and MQ IV) protein peaks. MQ III, which was eluted with 51% NaCl, exhibited gonadotropin releasing hormone activity. Surprisingly, unadsorbed fractions, MQ I, also showed gonadotropin releasing hormone activity. MQ 1 was therefore subjected to FPLC Mono S (a cation exchanger) column chromatography where a highly active gonadotropin releasing hormone enriched peak, i.e., MS III, could be eluted with 45% NaCl. These findings show thatCatla catla hypothalamus has two forms of gonadotropin releasing hormones one anionic (carp gonadotropin releasing hormone I) and another cationic (carp gonadotropin releasing hormone II). These two forms of gonadotropin releasing hormones were also active in heterologous carp species, rohu(Labeo rohita), mrigal(Cirrhinus mrigala) and an exotic common carp(Cyprinus carpio). Combined activity of two forms of gonadotropin releasing hormones was significantly greater as compared to any of the single form.     

Biochemical and stress responses of rohu Labeo rohita and mrigal Cirrhinus mrigala in relation to acclimation temperatures

The biochemical and stress responses of two Indian major carps, rohu Labeo rohita and mrigal Cirrhinus mrigala were studied after acclimating them to four preset temperatures (26, 31, 33 and 36° C) for 30 days. The blood glucose and liver glycogen levels showed an inverse trend in both the species and were significantly different in L. rohita at higher temperatures. The decrease in the liver glycogen level of C. mrigala , however, was not significant. Plasma cortisol levels increased significantly whereas the ascorbic acid content in the brain and kidney of both the species decreased significantly with increasing temperatures. Total lipid content in the liver of both the species decreased significantly with increasing acclimation temperatures. The phospholipid concentration decreased in L. rohita with increasing acclimation temperatures, and in C. mrigala the values decreased up to 33° C and increased at 36° C. In C. mrigala , the cholesterol level decreased up to 33° C and then increased at 36° C, but the absolute value was lower in comparison to L. rohita . The cholesterol levels, however, were not significantly different in L. rohita . Triglycerides and free fatty acids concentrations decreased significantly with increasing acclimation temperatures in both the species. The present study indicates species-specific metabolic responses of L. rohita and C. mrigala to thermal acclimation.     

Influence of serotonin on the action of melatonin in MIH-induced meiotic resumption in the oocytes of carp Catla catla

The influences of serotonin (5-hydroxytryptamine) on the action of melatonin (N-acetyl-5-methoxytryptamine) in MIH (maturation inducing hormone)-induced meiotic resumption were evaluated in the oocytes of carp Catla catla using an in vitro model. Oocytes from gravid female carp were isolated and incubated separately in Medium 199 containing either (a) only melatonin (MEL; 100 pg/mL), or (b) only serotonin (SER; 100 pg/mL), or (c) only MIH (1 microg/mL), or (d) MEL and MIH (e) or MEL (4 h before) and MIH, or (f) MEL and SER, (g) or SER and MIH, or (h) SER (4 h before) and MIH, or (i) luzindole (L-antagonist of MEL receptors; 10 microM) and MEL, or (j) MEL, L and MIH, or (k) MEL (4 h before), L and MIH, or (l) metoclopramide hydrochloride (M-antagonist of SER receptors; 10 microM) and SER, or (m) M, MEL, SER, or (n) M, SER and MIH, or (o) M, SER (4 h before) and MIH, or (p) M, MEL SER and MIH, or (q) MEL, L, SER and M, or (r) MEL, L, SER, M, and MIH, or (s) MEL, SER, L and MIH. Control oocytes were incubated in the medium alone. Oocytes were incubated for 4, or 8, or 12, or 16 h and effects were evaluated by considering the rate (%) of germinal vesicle breakdown (GVBD). At the end of 16 h incubation, 93.24+/-1.57% oocytes underwent GVBD following incubation with only MIH, while incubation with only MEL or only SER resulted in 77.15+/-1.91% or 14.42+/-0.43% GVBD respectively. Interestingly, incubation with MEL 4 h prior to addition of MIH in the medium, led to an accelerated rate of GVBD (92.58+/-1.10% at 12 h). In contrast, SER, irrespective of its time of application in relation to MIH, resulted in a maximum of 64.57+/-0.86% GVBD. While L was found to reduce the stimulatory actions of melatonin, M suppressed the inhibitory actions of serotonin. In each case, both electrophoretic and immunoblot studies revealed that the rate of GVBD was associated with the rate of formation of maturation promoting factor (a complex of two proteins: a regulatory component--cyclin B and the catalytic component--Cdk1 or cdc2). Collectively, the present study reports for the first time that SER not only inhibits the independent actions of MIH, but also the actions of MEL on the MIH-induced oocytes maturation in carp.     

The effect of insulin on intracellular ph and ribosomal protein S6 phosphorylation in oocytes of Xenopus laevis

Both insulin and progesterone are capable of stimulating germinal vesicle breakdown (GVBD) of large, Stage VI oocytes of Xenopus laevis. Numerous studies have shown an increase in intracellular pH (pHi) and ribosomal protein S6 phosphorylation prior to GVBD in oocytes treated with progesterone. In this study the effect of insulin and progesterone on pHi and S6 phosphorylation was compared. Both hormones increased pHi and S6 phosphorylation to similar levels and the time course of pHi change was the same for both hormones. Half-maximal effects of insulin were observed at 7 X 10(-8) M concentrations. In the presence of 1 nM cholera toxin, the ability of progesterone to induce these two responses was inhibited while the action of insulin was unaffected. However, GVBD induced by either hormone was blocked by cholera toxin. In small, Stage IV oocytes that do not undergo GVBD in response to either progesterone or insulin, a partial increase in pHi without S6 phosphorylation occurred in response to progesterone but both events occurred in response to insulin. These results suggest that the inability of Stage IV oocytes to undergo GVBD in response to hormone is not due to a failure to increase pHi or phosphorylate S6. The results in this paper also indicate that these events are regulated differently by insulin and progesterone in Xenopus oocytes.     

中华大蟾蜍卵母细胞成熟过程中膜电位变化的实验分析

The full-grown oocytes obtained from toad (bufo bufo gargarizans) submitted in hibernation state or reared at 25-30 degrees C for several months, named hibernation oocyte or high temperature oocyte, had a membrane potential of -41.51 +/- 0.77 mV and -43.83 +/- 1.39 mV in Ringer's solution respectively. The hibernation oocytes underwent GVBD (germinal vesicle breakdown) and membrane depolarization at 19 +/- 1 degree C after progesterone stimulation. The membrane potential was about -20 mV at the period of GVBD, and -10 mV or so at 20 hours after the hormone treatment. However, the high temperature oocytes did not undergo GVBD, their membrane potential decreased before the fourth hour after treatment with progesterone and then recovered. If the hibernation oocytes were preincubated at 37-38 degrees C for 13 hours prior to the culture in the medium containing progesterone (10(-6)M, 37-38 degrees C), no GVBD was observed and the membrane depolarized before the fourth hour after treatment with progesterone then recovered, but MPF was detectable in the cytoplasm (unpublished). Both GVBD and membrane depolarization appeared in the hibernation oocytes and high temperature oocytes after injection of MPF. The time required for the hibernation oocytes injected MPF to attain the membrane potential about -20 mV was 4 hours earlier than that of progesterone treatment. It was just the time required for the appearance of MPF in the cytoplasm of oocytes treated with the hormone. It was noticed in our precedent article that a factor which appeared in the cytoplasm of high temperature oocytes differed from MPF. The factor was called Hibernation Oocyte Mature Promoting Factor (HOMPF).(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparative tissue ascorbic acid studies in fishes

Comparative tissue ascorbic acid levels in four species of major carp viz., Labeo rohila, L. calbasu, Cirrhina tnrigala and Catla catla , were investigated. The ascorbic acid level was found to be the highest in the spleen in the four species studied (range 430–380 μg/g) followed by the anterior (adrenal) kidney, gonads, liver, renal kidney, brain and/or eye. Heart and blood had the lowest levels (range 26–18 μg/ml) amongst the tissues studied. Overall tissue ascorbic acid levels were the highest in L. rohita and the lowest in C. mrigala . Investigation on seasonal variations in blood and kidney ascorbic acid levels of Notopterus notopterus revealed peak levels in spring (February-April) and the lowest levels in the postspawning period (August-September).     

Inadvertent hybridization in a carp hatchery as detected by nuclear DNA RFLP

The Indian Major Carps Catla catla, Labeo rohita and Cirrhina mrigala , when spawned together in a 'spawning pool', hybridized at an estimated frequency of about 10%. The F _l hybrids of these species lack any improved economic traits but are fertile and can backcross with the parental species causing genetic introgression.     

Hypoxia inhibits fish spawning via LH-dependent final oocyte maturation

To evaluate the effects of long term hypoxia exposure on fish spawning, mature common carp, Cyprinus carpio carpio (Linnaeus) were subjected to either normoxia (7.4+/-0.2 mgO(2)mg O(2) L(-1)) or hypoxia (1.0+/-0.2 mgO(2)O(2) L(-1)) for more than two months. Gonadosomatic index (GSI), and concentrations of serum luteinizing hormone (LH), testosterone (T), and estroldiol (E2) were measured and gonad histology examined. Hypoxia inhibits fish spawning even though the gonad and oocytes developed under hypoxia exposure. LH levels of female carp were significantly decreased upon chronic exposure to hypoxia, and the final oocyte maturation in hypoxic females was significantly retarded. The results indicated that hypoxia may inhibit fish spawning through LH-dependent final oocyte maturation. In addition, no courtship was observed in hypoxic males. In conclusion, hypoxia impairs fish ovulation and, therefore, spawning and reproduction. LH levels were reduced leading to a failure of oocyte maturation. This, along with a lack of courtship by males may be the major mechanisms involved in hypoxic inhibition of reproduction in carp.     

Inhibition of LH-induced and spontaneous meiotic maturation in mouse oocytes by N alpha-tosyl-L-lysine chloromethylketone

The effect of N alpha-tosyl-L-lysine chloromethylketone (TLCK), an inhibitor of trypsin-type proteases, on luteinizing hormone (LH)-induced and spontaneous meiotic maturation and follicular production of cAMP in mice was determined. When follicle-enclosed mouse oocytes were incubated with LH (1 micron/ml), they underwent the breakdown of the germinal vesicle (GVBD). TLCK (0.02-0.5 mM) inhibited LH-induced GVBD in folliculated oocytes. The concentration (0.5 mM) of TLCK that inhibited LH-induced GVBD did not significantly suppress LH-induced cAMP production by follicle cells. The effect of TLCK on spontaneous maturation in cumulus cell-enclosed and denuded oocytes was also determined. TLCK strongly inhibited spontaneous maturation in denuded oocytes only if it was added to the incubation medium for 1-3 h before oocytes were liberated from the follicular tissue. The inhibition of oocyte maturation by TLCK was significantly greater in cumulus cell-enclosed oocytes than in denuded oocytes, either with or without preincubation with TLCK. These results suggest that trypsin-type protease in oocytes participates in the process of meiotic maturation in mouse oocytes.     

Cyclic AMP-mediated control of oocyte maturation in the catfish, Clarias batrachus (Bloch): effects of 17 alpha,20 beta-dihydroxy-4-pregnen-3-one and phosphodiesterase inhibitors

An increase in the percentage of germinal vesicle breakdown (GVBD) with a corresponding decrease in cAMP was found in the oocytes which were incubated for 36 hr with different concentrations of 17 alpha,20 beta-dihydroxy-4-pregnen-3-one (17 alpha,20 beta-DP). At its highest concentration (1 microgram/ml), 17 alpha,20 beta-DP induced 91.9 +/- 2.3% GVBD and decreased cAMP level to 0.8 +/- 0.1 pmol/oocyte from 2.9 +/- 0.2 pmol/oocyte (control). The two different known inhibitors of phosphodiesterase viz. 3-isobutyl-1-methyl-xanthine (IBMX) and theophylline inhibited GVBD in vitro and promoted the accumulation of cAMP in a dose-dependent manner irrespective of whether the oocytes were treated for a short duration (2 hr) or for a long duration (36 hr). Evaluation of time course response to 1 mM IBMX or 1 mM theophylline revealed that cAMP levels increased at all the time points when compared with their respective controls and blocked maturation. In contrast, 1 microgram/ml 17 alpha,20 beta-DP not only induced oocyte maturation but also caused an immediate decrease in cAMP within the first 2 hr (from 3.2 +/- 1.3 to 1.3 +/- 0.1 pmol/oocyte) of incubation which was maintained till the end of experiment (36 hr). Likewise, a significant inhibition of GVBD and accumulation of cAMP was recorded even in oocytes pre-stimulated with 1 microgram/ml 17 alpha,20 beta-DP for 6 hr and then treated with different concentrations of IBMX or theophylline. Taken together, these data strongly suggest that in C. batrachus a decrease of oocyte cAMP concentration is a prerequisite for the induction of oocyte maturation, and its increase is associated with the maintenance of meiotic arrest.     

Utilization of fermented silkworm pupae silage in feed for carps

Fermented silkworm pupae (SWP) silage or untreated fresh SWP pastes were incorporated in carp feed formulations replacing fishmeal. The feed formulations were isonitrogenous (30.2-30.9% protein) and isocaloric (ME = 2905-2935 kcal/kg). Feeding under a polyculture system consisting of 30% each of catla (Catla catla), mrigal (Cirrhinus mrigala) and rohu (Labeo rohita) with 10% silver carps (Hypophthalmychthys molitrix) was carried out in ponds to evaluate the nutritive quality of SWP silage. Survival rate, feed conversion ratio and specific growth rate, respectively, were 84.2%, 2.10 and 2.39 for fermented SWP silage, 65.8%, 2.98 and 2.26 for untreated SWP and 67.5%, 3.16 and 2.20 for fishmeal indicating clearly that the fermented SWP silage was nutritionally superior to untreated SWP or fishmeal. The dietary influence on the proximate composition of whole fish was marginal.     

Cumulus cells of oocyte-cumulus complexes secrete a meiosis-activating substance when stimulated with FSH

The effect of the different follicular cell types on resumption of meiosis was studied during stimulation with FSH. Cumulus enclosed oocytes (CEO), denuded oocytes (DO), and cumulus and mural granulosa cells were used. The resumption of meiosis and oocyte maturation were assessed by the determination of the germinal vesicle breakdown (GVBD) and polar body formation (PB) at the end of a 24 hr culture period in the presence of 4 mM hypoxanthine (HX). The effects of recombinant LH (r-LH) and hCG were also evaluated. Oocyte exposure to the gonadotrophins varied from 5 min to 24 hr (i.e., priming time). Oocytes were obtained from immature gonadotrophin-stimulated and -unstimulated mice. 1. FSH (1 IU/L-75 IU/L) provoked a dose-dependent increase in GVBD and PB in CEO, but not in DO, in stimulated and unstimulated mice. Eight IU/L was sufficient for inducing resumption of meiosis. In contrast, LH and hCG (both 1 IU/L-1500 IU/L) were without effect on GVBD and PB in CEO and DO of oocytes from stimulated and unstimulated mice. A combination of 8IU/L FSH and 4–8 IU/L hCG produced an additive effect, whereas combinations with LH and higher concentrations of hCG had no such effect. 2. A 2 hr priming with FSH (8 IU/L-75 IU/L) induced a dose-dependent oocyte maturation in CEO. Thirty minutes of priming with FSH (75 IU/L) was sufficient for induction of meiotic resumption in CEO. 3. Priming CEO with FSH for 2 hr followed by the separation and repooling of oocytes and cumulus cells induced oocyte maturation. GVBD of new, unprimed DO added to cumulus cells of primed CEO increased slightly but was significant, whereas GVBD in DO isolated from the primed CEO only increased marginally. DO cocultured with FSH-primed cumulus masses seem to be prevented from resuming meiosis. 4. Priming a coculture of granulosa cells and DO with FSH for 2 hr caused a significant increase in GVBD compared to the control, evaluated after 24 hr. In contrast, a 24 hr FSH-priming of a coculture of granulosa cells and DO was without effect on GVBD. 5. A spent medium in which unstimulated cumulus cells or mural granulosa cells had grown was without effect on GVBD in DO. However, a small fraction of the DO resumed meiosis after culture in a spent medium derived from a 2 hr priming of CEO and spent media from 24 hr priming of CEO induced a 2–3 times higher GVBD frequency in the DO compared to the controls. Heat treatment of spent media (70°C, 30 min) from a 24 hr FSH-priming of CEO still induced GVBD in naive DO. The results showed that FSH, in a concentration of as little as 8 IU/L, but not r-LH and hCG, induced within 30 minutes the cumulus cells to produce and after 2 hr to secrete a diffusible heat stable meiosis activating substance. This substance overcame, in a paracrine fashion, the inhibiting effect of HX and induced oocyte maturation directly in DO. The production of this substance, however, was dependent on the initial connection between the cumulus cells and the oocyte, indicating an important 2-way communication between these 2 cell types. The mural granulosa cells did not produce a meiosis inducing activity by stimulation with FSH, but significantly, more DO matured after coculture with the nonstimulated granulosa cells for 24 hr than for 2 hr. It is proposed that the heat stable meiosis activating component of the spent media from the FSH-stimulated CEO belongs to the meiosis activating sterols, MAS, previously isolated from human follicular fluid and from adult bull testes. Mol. Reprod. Dev. 46:296–305, 1997. © 1997 Wiley-Liss, Inc.     

Factors influencing resumption of meiotic maturation and cumulus expansion of porcine oocyte-cumulus cell complexes in vitro

The present study was undertaken to examine effects of various combinations of epidermal growth factor (EGF), transforming growth factor-b?₁ (TGF-b?₁), follicle-stimulating hormone (FSH), luteinizing hormone (LH), androstenedione (A₄), and estradiol-17b? (E₂) on meiotic maturation and cumulus expansion in the pig using an in vitro model system. Oocyte-cumulus cell complexes (OCC) were cultured in the media containing the abovementioned agents for 24 hr and were observed for germinal vesicle breakdown (GVBD), indicative of initiation of meiotic maturation, and for expansion of their cumulus cells. Treatment with EGF significantly increased (P < 0.05) incidence of GVBD, with maximal stimulation occurring at 1 ng/ml (55% vs. 12% in the control). Concentrations of EGF as low as 100 pg/ml significantly stimulated GVBD over control (37% vs. 12%). Addition of EGF (1 ng/ml) and FSH (1.5 μg/ml) together and LH (2 μg/ml) and FSH (1.5 μg/ml) together resulted in significantly higher (P < 0.01) GVBD levels than were observed in response to EGF, FSH, or LH alone. Addition of E₂ (1 μg/ml) had no effect by itself but significantly decreased the incidence of GVBD in the presence of FSH and of LH + FSH. Addition of A₄ (1 μg/ml) significantly reduced the percentage of oocytes undergoing GVBD when added alone or with FSH. Although both EGF and LH stimulated cumulus expansion, FSH was more effective in stimulating cumulus expansion than EGF or LH. TGF-b?₁ had no effect on GVBD or cumulus expansion. These studies indicate that these hormones may have differing roles in oocyte maturation and that their interactions may be part of an intricate system regulating the maturation of oocytes during follicular development in vivo. © 1993 Wiley-Liss, Inc.     

Temporal relations between plasma concentrations of luteinizing hormone, follicle-stimulating hormone, estradiol-17beta, progesterone, prolactin, and alpha-melanocyte-stimulating hormone during the follicular, ovulatory, and early luteal phase in the bitch

Compared with other domestic animals, relatively little is known about the changes in, and temporal relations between, reproductive hormones around the time of ovulation in the domestic bitch. Therefore, plasma concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol-17beta, progesterone, prolactin (PRL), and alpha-melanocyte-stimulating hormone (alpha-MSH) were determined one to six times daily from the start of the follicular phase until 5 days after the estimated day of ovulation in six Beagle bitches. In all bitches, the pre-ovulatory LH surge was accompanied by a pre-ovulatory FSH surge. A pre-ovulatory PRL or alpha-MSH surge was not observed. The pre-ovulatory FSH and LH surges started concomitantly in four bitches, but in two bitches the FSH surge started 12 h earlier than the LH surge. The FSH surge (110+/-8 h) lasted significantly longer than the LH surge (36+/-5 h). In contrast with the pre-ovulatory FSH surge, the pre-ovulatory LH surge was bifurcated in four of six bitches. The mean plasma LH concentrations before (1.9+/-0.4 microg/L) and after (1.9+/-0.3 microg/L) the LH surge were similar, but the mean plasma FSH concentration before the FSH surge (1.6+/-0.3 U/L) was significantly lower than that after the FSH surge (3.1+/-0.2 U/L). In most bitches the highest plasma estradiol-17beta concentration coincided with or followed the start of the pre-ovulatory LH surge. In five of the six bitches the plasma progesterone concentration started to rise just before or concurrently with the start of the LH surge. In conclusion, the results of this study provide evidence for the differential regulation of the secretion of LH and FSH in the bitch. In addition, the interrelationship of the plasma profiles of estradiol-17beta and LH suggests a positive feedback effect of estradiol-17beta on LH surge release. The start of the pre-ovulatory LH surge is associated with an increase in the plasma progesterone concentration in this species.     

Nitrite toxicity in Indian major carps: sublethal effect on selected enzymes in fingerlings of Catla catla, Labeo rohita and Cirrhinus mrigala

The effects of 96-h sublethal exposure of nitrite (1, 2, 4, 8 and 10.4 mg l(-1)) on selected enzymatic activities in serum and tissues of fingerlings of catla (Catla catla), rohu (Labeo rohita) and mrigal (Cirrhinus mrigala) were studied for the first time in these species. All three species responded almost identically to nitrite exposure. With increasing nitrite concentration, reduction in activities was observed in acetylcholinesterase (AChE) in brain and liver; alkaline phosphatase (ALP) in serum, brain and gill; and acid phosphatase (ACP) in gill, while progressive increase in alanine aminotransferase (ALAT) and aspartate aminotransferase (ASAT) activities in brain, gill and serum, and ACP activity in serum and brain was observed. Lactate dehydrogenase (LDH) activity increased in gill, liver, kidney, brain and serum of all three species with increasing nitrite concentration up to 8 mg l(-1) followed by reduction at 10.4 mg l(-1). The study revealed nitrite stress causing alteration in activities of all measured tissue and serum enzymes in the fingerlings, and so stresses the need for proper management of this particular nutrient in water during carp culture.     

Differential regulation of the secretion of luteinizing hormone and follicle-stimulating hormone around the time of ovulation in the bitch

Plasma concentrations of luteinizing hormone (LH) and follicle stimulating hormone (FSH) were determined 3-6 times daily in six Beagle bitches from the start of the follicular phase until 5 d after the estimated day of ovulation. The aim of the study was to gain more detailed information regarding the changes in and the temporal relation between these hormones around the time of ovulation. In all bitches, the pre-ovulatory LH surge was accompanied by a pre-ovulatory FSH surge. The mean duration of the pre-ovulatory FSH surge (110 +/- 8 h) was significantly longer than that of the pre-ovulatory LH surge (36 +/- 5 h). The FSH surge started concomitantly with the pre-ovulatory LH surge in four bitches, and 12 h before the start of the LH surge in the other two bitches. The pre-ovulatory LH surge had a bifurcated pattern in four bitches. The mean plasma LH concentration before (1.9 +/- 0.4 microg/L) and after (1.9 +/- 0.3 microg/L) the pre-ovulatory LH surge were similar. The mean plasma FSH concentration during the period 72-28 h before the pre-ovulatory LH surge (1.6 +/- 0.3 U/L) was lower (P < 0.001) than that during the period 100-144 h after the pre-ovulatory LH surge (3.1 +/- 0.2U/L). In conclusion, this study demonstrated concurrent pre-ovulatory surges of FSH and LH and provided more evidence for differential regulation of the secretion of FSH and LH.