Spleen immune status is affected after acute handling stress but not regulated by cortisol in Eurasian perch,Perca fluviatilis

The effects of acute stress on immune status and its regulation by cortisol/corticosteroid receptors have received little attention in percids. To address that question, we investigated the physiological and immune responses of Eurasian perch, Perca fluviatilis to acute stress. We exposed immature perch to an 1-min exondation and measured at 1 h, 6 h, 24 h and 72 h post-stress: (1) stress-related parameters including plasma cortisol and glucose levels, (2) immune parameters in the plasma and in the spleen (complement, respiratory burst and lysozyme activity, total immunoglobulins; gene expression of lysozyme, complement unit 3, apolipoprotein A1 and 14 kDa, hepcidin and chemotaxin) (3) the corticosteroid receptors gene expression in the spleen after having cloned them. In addition, the in vitro effects of cortisol on the spleen immune parameters were also investigated.Plasma cortisol and glucose levels increased markedly 1 h post-stress and returned at basal levels after 24 h. P. fluviatilis mineralocorticoid receptor, but not glucocorticoid receptors, was significantly up-regulated both in vivo after the stress and in vitro by cortisol at a physiological concentration (100 ng/ml). The plasma immune parameters were not significantly affected by the stress. In contrast, spleno-somatic index, spleen lysozyme activity, lysozyme and hepcidin gene expression were depleted and total immunoglobulins increased along the whole time-course (1–72 h). But, these immune parameters were not regulated in vitro by cortisol at physiological or supra-physiological doses.Our results indicate that handling stress may affect spleen antibacterial defences without clear effects on circulating immune compounds and that the elevation of plasma cortisol after handling stress may not be related to the regulation of this splenic response.     

Does domestication process affect stress response in juvenile Eurasian perch Perca fluviatilis?

The objective was to evaluate the impact of domestication process on the physiological stress response of cultured Eurasian perch confronted to a chronic stress situation. Briefly, F1 and F4 juveniles were submitted to chronic confinement and investigated on days 5, 15 and 30. Capture and 15min-anesthesia were imposed on fish to assess the effect of preceding confinement on acute stress response. On day 30, the fish were finally challenged with Aeromonas hydrophila and sampled after 5 and 10 days for immune parameter measurements. Cortisol and glucose levels were not affected by confinement but increased significantly after acute stressor exposure. Moreover, cortisol rise following capture and anesthesia was higher in F1 confined-fish, suggesting that they have previously been affected by chronic confinement. A higher HSP70 level was also observed on day 30 in F1 confined-juveniles. During bacterial challenge, regardless of confinement level, F4 juveniles displayed higher lysozyme activity and agglutination response than F1 which may indicate a higher immune capacity in domesticated fish. In conclusion, chronic confinement stressor induced few physiological responses but may increase the responsiveness to other aquacultural stressors. Domestication process also seems to improve chronic stress resistance, growth as well as the immune status of the fish.     

Carbon and Nitrogen Mineralization of Lead Treated Soils in the Eastern Mediterranean Region,Turkey

The aim of this study was to determine the first effect of lead on microbial activity in soil. The study was carried out in the soil samples from four different radish (Raphanus sativus L. var. radicula, Brassicaceae) fields along the highway in a district (Kadirli, Osmaniye) of the Eastern Mediterranean Region, Turkey. After the calculation of Pb contents, the Pb amounts of the soil samples were brought up to 50 and 100 mg Pb kg^?1 by treatment with Pb(NO ₃ ) ₂ , and the samples for the carbon and the nitrogen mineralization were incubated under controlled conditions (28°C, constant moist). The carbon mineralization was determined by a CO ₂ respiration method for 30 days. The nitrogen mineralization was observed in vitro for 6 weeks. The untreated group was statistically different from the 50 and 100 mg Pb kg^?1 treatments in the aspect of the C(CO ₂ ) outlet during mineralization (P ≤ 0.05), but difference between the 50 and 100 mg Pb kg^?1 treatments was not significant. NH ₄ -N and NO ₃ -N contents of each soil were shown differences between across treatments. Based on these results, it is possible to conclude that the addition of 50 and 100 mg Pb kg^?1 provided a toxic effect threshold for the microbial activity into 30 days.     

Incidence of mycoflora and mycotoxins in some edible fruits and seeds of forest origin

Twelve fungi namelyAlternaria alternata, Aspergillus flavus, A niger, A ochraceus, Actinomucor repens, Capnodoium spp., Curvularia lunata, Fusarium pallidoroseum, F solani, F verticillioides, Penicillium citrinum and Rhizopus stolonifer were recorded from samples ofAegle marmelos, Aesculus indica, Buchanania lanzan andPinus gerardiana. In case ofPrunus amygdalus only Rstolonifer was recorded. A significant variation in pattern of mycoflora incidence was observed in terms of source and season. Fungal infestation in most of the substrates was found to be highest during monsoon. Aflatoxins were the most common mycotoxins elaborated by different isolates ofA flavus obtained fromA marmelos, B lanzan andP gerardiana. The amount of aflatoxins produced by the toxigenic isolates ofA flavus was in the range of traces to 0.9–26.0 μg/ml inA marmelos, 0.8–17.5 μg/ml inP gerardiana and 0.65–13.2 μg/ml inB lanzan. The percentage toxigenicity was comparatively lower in the isolates of other mycotoxigenic fungi. Aflatoxins were detected almost in all the samples analyzed for mycotoxin contamination. However, traces of zearalenone were detected inA marmelos. The concentration of aflatoxin B₁ was in the range of 0.13–0.75 μg/g inA marmelos, 0.09–0.60 μg/g inP gerardiana and 0.01–0.20 ug/g inB lanzan. Mycotoxins were not detected inAesculus indica andPrunus amygdalus.     

Effects of suckling mode on endocrine control of reproductive activity resumption in Texel ewes lambing in July or November

To study the effects of the overlapping of seasonal and lactation anestrus and the influence of the suckling mode on the resumption of reproductive activity in Texel ewes, two experiments were carried out after the July and November lambings. The frequency and the duration of suckling decreased with the age of the lambs, and the suckling intensity in the lambs that were allowed to suck unrestrictedly was three times higher than in lambs restricted to sucking three times a day. The overlapping of seasonal anestrus and lactation delayed the resumption of ovarian and estrus activity, but no difference was observed between dams suckling single lambs and twins. The resumption of ovarian and estrus activity was much earlier after the November lambing than after the July lambing. Weaning after the November lambing shortened the interval between parturition to first estrus but not to the first luteal function. The reduction of suckling intensity by suckling management had no effect on the resumption of ovarian and estrus activity. In early postpartum, suckling inhibited the luteinizing hormone (LH) pulsatile secretion and consequently the first LH discharge. However, the earlier restoration of gonadotropin stimulation in dry ewes was not immediately followed by ovarian activity. The suckling inhibition may be due to a temporary disturbance in hormonal balance, the rise in prolactin (PRL) and cortisol secretions. Plasma estradiol 17beta (E2) concentrations were higher in dry than in suckling ewes in early postpartum. Follicle stimulating hormone (FSH) secretion was not involved in the process of delaying the resumption of reproductive activity after lambing.     

Pre-ovulatory follicular characteristics and ovulation rates in different breed crosses, carriers or non-carriers of the Booroola or Cambridge fecundity gene

Terminal follicular dynamics and ovulation rates (OR) were compared in different local breeds after introducing fecundity genes of different origin. Crossbred ewes which were carriers (F+) or non-carriers (++) of Booroola (BFec) or Cambridge genes (CFec) were included: CambridgexCambridge (CC), CambridgexSuffolk (CS), CambridgexTexel (CT), BooroolaxTexel (BT) and BooroolaxGerman Mutton Merino (BGM). The numbers of small (diameter 2-3.5 mm), medium (diameter >3.5-5.0 mm) and large (diameter >5.0 mm) growing follicles, the maximum diameter before ovulation and the regression and artesia rates of ovarian follicles >/=2 mm in diameter were studied laparoscopically and repeatedly during the last 5 days of an induced oestrous cycle. The ORs were determined one cycle before and two cycles after the repeated laparoscopy. BFec and CFec significantly enhanced the OR of all crossbreeds. Carriers of BFec or CFec did not have significantly different ORs due to any crossbreeding effect. The same observation was made for non-carriers of both Fec gene types. Whatever the crossbreed, the number of small, medium and large growing follicles were similar between carriers and non-carriers in spite of a higher number of ovulating follicles in carriers of both Fec gene types. The diameter of ovulatory follicles did not differ among crossbreds, or between carriers and non-carriers except in the BT (5.2+/-0.2 vs. 6.5+/-0.8 mm, respectively) and CC (6.6+/-0.2 vs. 5.6+/-0.3 mm) ewes.The higher OR in the presence of the Booroola gene was associated with a low atresia rate of large follicles in all crossbreeds (BT: 52+/-8% (F+) vs. 61+/-7% (++); BGM: 51+/-6% vs. 75+/-5%). The high OR of the carriers of the CFec gene seemed to be associated with a lower number of large growing follicles with a lower (P<0.05) atresia rate as compared with Booroola crossbreeds.In conclusion, follicular features were similar between purebred Cambridge and its crossbred CS and CT. In ewes carrying the BFec or CFec gene, the reduction in follicular atresia seemed to be one of the main follicular features implicated in the higher OR.