Seasonal variation in haematological parameters in male and female Tinca tinca

This study was designed to investigate any seasonal (spring, summer, autumn and winter) changes in haematological parameters in the blood of Tinca tinca measuring the number of red blood cells (RBC), haematocrit, white blood cells, and total plasma proteins.The results show significant changes in RBC and haematocrit in males comparing spring and summer with autumn and winter, whereas in females the RBC remained constant for all 4 seasons but the haematocrit decreased in autumn and winter compared to spring and summer. The white blood cells of male and female animals were significantly lower in spring and winter compared to summer and autumn. In male fish total protein contents significantly decreased in autumn and winter compared to spring and summer, whereas in females protein output significantly decreased in winter compared to the other seasons. The results indicate marked seasonal variation in the blood of male and female Tinca tinca. This variation may play a important protective role for the survival of the animals.     

Effect of Ca2+ on deformation, polar body extrusion and pronucleus formation in the egg of the ascidian, Ciona savignyi

Cortical deformation and polar body extrusion are the principal events that occur at fertilization in the ascidian egg. We demonstrated that the intracellular Ca²⁺ concentration ([Ca²⁺]_i) in the fertilized egg of Ciona savignyi increased at egg deformation (main peak) and then several small Ca²⁺ spikes (1st spikes) appeared before the first polar body extrusion. Brief Ca²⁺ spikes (2nd spikes), then appeared in the period between the first and second polar body extrusion. When eggs were fertilized in Ca²⁺-free artificial seawater, the main peak and 1st spikes appeared, but the 2nd spikes did not, suggesting that the Ca²⁺ required for the main peak and 1st spikes is released from the intracellular store in this species and that extracellular Ca²⁺ is required for the 2nd spikes. When [Ca²⁺]_i was clamped at a low level (0.03–0.13 μmol/L) by injecting the egg with low-Ca²⁺ buffers and the egg was then inseminated, deformation, polar body extrusion and pronucleus formation were suppressed. In contrast, egg deformation and first polar body extrusion were induced without insemination when [Ca²⁺]_i was 0.9 μmol/L. A higher Ca²⁺ concentration of 1.2–10.1 μmol/L was required for extrusion of the second polar body and pronucleus formation. These data suggest that sequential Ca²⁺ increases (i.e. main peak and 1st and 2nd spikes) are prerequisite for the deformation and polar body extrusion of the egg. Furthermore, in eggs arrested at the second meiotic metaphase after first polar body extrusion by the injection of Ca²⁺ buffer, subsequent injection of excess Ca²⁺ caused formation of an irregular second polar body-like protrusion, suggesting latent arrest at the second meiotic metaphase in the ascidian egg.     

活酵母衍生物对丁(鱼岁)抗氧化能力和部分免疫活性指标的影响

在饲料中添加0.4%活酵母衍生物(LYCD)喂养丁(Tincatinca),对该鱼超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、氧化代谢产物丙二醛(MDA)以及溶菌酶(LYZ)等指标进行测定。结果表明:LYCD可显著提高机体的抗氧化能力;促进鱼体SOD酶的产生,试验与对照组鱼鳃SOD酶活性表现出极显著差异,肝胰脏和脾脏SOD酶的含量显著提高;试验组肝胰脏CAT酶活性极显著升高而氧化代谢产物MDA则极显著下降,脾脏也有显著差异;试验组鱼鳃和肝胰脏组织LYZ活性极显著高于对照组,脾脏LYZ活性也显著提高,而肾脏没有明显变化;同时LYCD还能增加白细胞的吞噬能力,白细胞吞噬指数明显增加     

Second meiotic division and polar body formation in mouse eggs fertilized in vitro

The second meiotic division and polar body formation in mouse eggs fertilized in vitro were observed by phase-contrast and polarizing microscopy, and recorded by time-lapse cinematography. Eggs were collected from oviducts of mice that had been superovulated by injections of PMS and HCG. Some eggs, inseminated with spermatozoa that had been collected from caudae epididymides of mature male mice and cultured for two to three hours before insemination, were observed continuously on a glass slide under a phase microscope. Other eggs were inseminated in Petri dishes in a 5% CO₂ incubator and examined every 20 minutes for 180 minutes. Compatible results in both sets of eggs showed that formation of the second polar body began 25–40 minutes after fusion of spermatozoon with the vitellus; it was completed 40–60 minutes later; anaphase II lasted approximately five minutes before the appearance of the furrow abstricting the second polar body. It is suggested that the furrowing associated with second polar body formation is guided by the same kind of forces that divide a cell mitotically.     

丁(鱼岁)的含肉率及其营养价值的分析

报道了丁的含肉率及鱼肉生化成分 ,并对其营养价值做了综合评价。丁含肉率达 73 59% ,鱼肉蛋白质含量为 19 73% ,脂肪含量为 1 2 9%。 17种氨基酸总含量为 18 13% ,其中 7种必需氨基酸总量为 7 0 4 %。丁肌肉所含人体必需氨基酸占氨基酸总量的百分比高于WHO FAO提出的标准。必需氨基酸指数为 74 38。     

MHC-linked susceptibility to a bacterial infection, but no MHC-linked cryptic female choice in whitefish

Non-random gamete fusion is one of several potential cryptic female choice mechanisms that have been postulated and that may enhance the survival probability of the offspring. Previous studies have found that gamete fusion in mice is influenced by genes of the major histocompatibility complex (MHC) region. Here we test (i) whether there is MHC-dependent gamete fusion in whitefish (Coregonus sp.) and (ii) whether there is a link between the MHC and embryo susceptibility to an infection by the bacterium Pseudomonas fuorescens. We experimentally bred whitefish and reared sibships in several batches that either experienced or did not experience strong selection by P. fluorescens. We then determined the MHC class II B1 genotype of 1016 surviving larvae of several full sibships. We found no evidence for MHC-linked gamete fusion. However, in one of seven sibships we found a strong connection between the MHC class II genotype and embryo susceptibility to P. fluorescens. This connection was still significant after correcting for multiple testing. Hence, the MHC class II genotype can considerably influence embryo survival in whitefish, but gamete fusion seems to be random with respect to the MHC.     

Diet composition and prey preference of tench, Tinca tinca (L.), common bream, Abramis brama (L.), perch, Perca fluviatilis L. and roach, Rutilus rutilus (L.), in two contrasting gravel pit lakes: potential trophic overlap with wildfowl

The abundance of benthic macroinvertebrate taxa and the relative abundance of zooplankton taxa were compared with the diet of bream, tench. perch and roach from two gravel pit lakes during May-July 1986 and 1987. Significant food preferences were demonstrated between species and between lakes. Chironomid pupae dominated the macroinvertebrate diet of perch, roach, ate predominantly either Spirogyra sp. (St Peters Lake) or Daphniu hyalina (Main Lake).
The Main Lake, bream fed largely upon chironomid larvae and the bivalve Sphuerium but in St Peters Lake they positively selected a variety of less abundant benthic invertebrate taxa. Bream switched from benthos to zooplankton in the Main Lake in 1986. Tench ate large numbers of Aselhs and showed positive selection of various macroinvertebrate prey in St Peters but ate D. hjulim in Main Lake. Tropic overlap for chironomids and other macroinvertebrate prey was demonstrated between perch, bream and tench, and potentially with wildfowl which used the gravel pits for breeding and wintering.     

丁不同群体间形态学差异与随机扩增多态DNA(RAPD)分析

采用聚类分析、主成分分析和判别分析3种数理统计方法,对我国新疆朱家湖丁群体7、3水库丁群体和从捷克引进我国的丁群体的可量性状和框架参数进行分析。聚类分析和主成分分析显示,朱家湖群体与73水库群体较为接近,而捷克群体与前两群体相距较远。判别分析亦可将捷克群体与前两群体分开,准确率达100%。从60个随机引物中筛选出的20个引物对丁朱家湖群体、73水库群体和捷克群体进行了随机扩增多态DNA(RAPD)分析。引物S440在捷克群体扩增出的450bp片段为该群体特有的标记片段。朱家湖群体、73水库群体、捷克群体多态位点比例分别为24%、22.67%和18.42%;群体内遗传相似度分别为0.8967、0.9035和0.9309;遗传多态度(π)分别为0.1539、0.1489和0.1142。表明朱家湖群体保持着较高的遗传变异。三群体间的遗传相似度为0.6868—0.9496,群体遗传分化系数(Fst)为0.048—0.238,分子方差分析发现群体内方差占总方差的83.96%,群体间的方差只占16.04%,由此推断三群体间遗传分化并不大。     

Influence of Light Intensity on Plasma Melatonin and Locomotor Activity Rhythms in Tench

Melatonin production by the pineal organ is influenced by light intensity, as has been described in most vertebrate species, in which melatonin is considered a synchronizer of circadian rhythms. In tench, strict nocturnal activity rhythms have been described, although the role of melatonin has not been clarified. In this study we investigated daily activity and melatonin rhythms under 12∶12 light‐dark (LD) conditions with two different light intensities (58.6 and 1,091 µW/cm²), and the effect of 1 h broad spectrum white light pulses of different intensities (3.3, 5.3, 10.5, 1,091.4 µW/cm²) applied at middarkness (MD) on nocturnal circulating melatonin. The results showed that plasma melatonin in tench under LD 12∶12 and high light conditions displayed rhythmic variation, where values at MD (255.8±65.9 pg/ml) were higher than at midlight (ML) (70.7±31.9 pg/ml). Such a difference between MD and ML values was reduced in animals exposed to LD 12∶12 and low light intensity. The application of 1 h light pulses at MD lowered plasma melatonin to 111.6±3.2 pg/ml (in the 3.3–10.5 µW/cm² range) and to 61.8±18.3 pg/ml (with the 1,091.4 µW/cm² light pulse) and totally suppressed nocturnal locomotor activity. These results show that melatonin rhythms persisted in tench exposed to low light intensity although the amplitude of the rhythm is affected. In addition, it was observed that light pulses applied at MD affected plasma melatonin content and locomotor activity. Such a low threshold suggests that the melatonin system is capable of transducing light even under dim conditions, which may be used by this nocturnal fish to synchronize to weak night light signals (e.g., moonlight cycles).     

Ooplasmic segregation and axis formation in the polychaeteNereis virens embryo

Ooplasmic segregation is of great importance in the development of Annelida. The mechanisms of this process are very diverse in different groups of polychaetes, oligochaetes, and leeches (Fernandezet al., 1998). Ooplasmic segregation inNereis virens is connected with the first meiotic spindle formation and animal-vegetative axis appearance. Spherical polyaxial symmetry of the oocyte transforms into radial stratified symmetry in the course of ooplasmic segregation. There are two main steps of ooplasmic segregation inNereis virens. The first step begins after the cortical reaction when the central clear cytoplasm reaches the surface of the oocyte. The movement of the cytoplasm is sensitive to nocodazole, colchicine, and cytochalasin B and appears to be mediated by microtubules and, partly, by microfilaments. The second step is not sensitive to the microtubule inhibitors and is mediated mainly by actin filaments. Ooplasmic segregation inNereis virens may be considered as a primitive form of ooplasmic segregation in Annelida.