刺参(Apostichopus japonicus)夏眠期间消化道的组织学研究

运用切片和扫描电镜技术对刺参夏眠状态和正常状态的消化道进行了组织学比较研究。结果表明,与正常状态下相比,进入夏眠后刺参消化道发生退化,消化道整体变细,变短。消化道各部分的界限变得不明显。消化道基本结构未发生变化,仍然由粘膜层、粘膜下层、肌层和外膜组成。但内表面柱状细胞变矮,皱襞减少,纤毛和微绒毛几乎完全脱落,分泌颗粒减少或消失。粘膜下层结缔组织变得稀疏,细胞数目减少。肌层变薄。外膜外表面的变化不大,但出现增厚的现象。对于不同夏眠阶段刺参消化道的区别有待于进一步研究。     

纹缟虾虎鱼对Cu~(2+)、Cd~(2+)和氨氮的毒性响应和敏感性分析

以纹缟虾虎鱼为受试生物,分别进行了Cu~(2+)、Cd~(2+)和氨氮为环境因子的急性毒性实验和氨氮慢性暴露实验,结合文献数据分析纹缟虾虎鱼对3种污染物的敏感性。结果表明,Cu~(2+)、Cd~(2+)和氨氮对纹缟虾虎鱼的EC50分别为4.527、40.408和63.182mg·L~(-1)。组织切片结果显示,氨氮暴露能够引起纹缟虾虎鱼肝组织结构退化,组织细胞畸变,其损伤程度随着氨氮浓度的升高而加剧。氨氮暴露对肠管未见明显影响。敏感性分析结果表明,纹缟虾虎鱼对Cu~(2+)、Cd~(2+)和氨氮的累积概率分别为83.33%、96.27%和90.48%,均表现为不敏感。在Cu~(2+)、Cd~(2+)和氨氮对海洋生物的敏感性排名中,纹缟虾虎鱼分别在第31/35、32/32和19/20位。在8~12种海洋鱼类中,纹缟虾虎鱼对上述3种污染物的敏感性都处在较低水平。     

Adult respiratory distress syndrome in human organophosphate poisoning cases

Adult respiratory distress syndrome (ARDS) is a clinical syndrome which occurs due to various direct or indirect noxious agents and pyhsical mechanisms. One of the etiological factors is ingested chemicals (e.g. paraquat, ethylene glycol). The organophosphorous (OP) insecticides are the most toxic and frequently encountered chemicals that produce poisoning in humans. Studies were undertaken to investigate whether OP insecticides may produce ARDS. Fifteen autopsy cases due to suicidal OP insecticide poisoning were investigated. Toxicological analyses were performed with a gas chromatography-nitrogen phosphorous detector (GC-NPD). Methamidophos, dimefox and dichlorvos were the detected OP. Lungs were examined macroscopically. Two cases showed features compatible with ARDS in which the only cause of death was OP poisoning. Due to the severity of ARDS it is important to assess insecticidal exposure in an attempt to enhance survival patterns following OP poisoning in patients in order to initiate therapy.     

Time-dependent effects of chlordane on thyroid histological structure and function in rats

In order to study the time-dependent effects of chlordane on thyroid hormone levels and histological structure in rats, 120 healthy 4-week-old SD rats were divided randomly into 12 groups. Rats in treatment groups were treated orally by gavage with chlordane at a dose of 15 mg kg^?1 for 5, 10, 15, 20, 30, or 40 days, while rats in control group received an equal volume of corn oil. Serum levels of thyroxine (FT4), triiodothyronine (FT3), and thyroid stimulating hormone (TSH) were measured by radioimmunoassay. Sections of thyroids were dyed with hematoxylin–eosin to detect any pathological alterations. In chlordane treated groups, on day 5, changes in serum levels of FT4, FT3, and TSH were not found. On days 10 and 15, serum levels of FT4 and FT3 decreased, accompanied by increased levels of TSH. On days 20, 30 and 40, serum levels of these hormones returned to control values. As for alterations in histology, on day 10–15, follicular epithelium of the thyroid were found to proliferate into two layers in chlordane treated rats. On day 20, in focal areas the two-layer afollicular epithelia were observed to continuously proliferate into 3–4 layers of follicular epithelium, termed hyperplasia plaques. On days 30 and 40, solid buds and secondary follicles to solid buds were detected. The earliest alteration of thyroid hormones in treated SD rats occurred between 5 and 10 days with corresponding histopathologic changes. As the exposure time increased, the serum levels of hormones and histopathology altered in a time-dependent manner.     

Studies on reflective features of Norway spruce and their possible applications in remote sensing of forest damage∗

Reflective features of Norway spruce have been studied as a part of a multi‐level experiment in order to assess and to develop methods for early forecasting of forest damages by remote sensing. Discoloration and histological changes were investigated by high resolution reflectance spectroscopy and true‐color image interpretation of histological cuts, respectively. Major changes of reflectances were detected in the visible spectral range 480–680 nm depending on degree of tree's damages and/or needle discoloration. Related histological changes depending on degree of tree's damage were hypertrophy of chloroplasts, plasmolysis and partial loss of compartmentalization. Development and use of several highly sensitive channels with narrow bandwidths between 480 and 680 nm, e.g. 480, 550, 680, 760 nm, for early assessment of forest damages by remote sensing could be recommended.     

Effects of ultraviolet radiation on skin structure and ultrastructure in Caspian Sea Salmon,Salmo trutta caspius,during alevin stage

Ozone reduction enhances the amount of ultraviolet (UV) radiation reaching the aquatic ecosystems, which can induce adverse effects on fish. In order to study the UV radiation effects on skin structure and ultrastructure, the alevins of Salmo trutta caspius were exposed to two different doses of UV radiation (low doses of: 60 µW cm^?2 UVC; 100 µW cm^?2 UVB; and 40 µW cm^?2 UVA and high doses of: 90 µW cm^?2 UVC; 130 µW cm^?2 UVB; and 50 µW cm^?2 UVA) for 15 min once a day in dark condition. Alevins with no exposure to either solar light or UV exposure served as the control group. No mortality was observed in the control group, whereas all of the alevins died in the 9th day in both UV exposure groups. Light microscopic and scanning electron microscopic studies showed significant reduction in the epidermis thickness, number of skin mucous cells, and percentage of mucus secreting cells in both UV exposure groups. Sunburn cells, lifting epidermis from basal membrane, and disappearance of pavement cell microridges were also observed. Our results showed that UV radiation caused intensive skin cell lesions in the Caspian salmon alevins. Since the skin cells of trout alevins possesses essential roles in respiration, osmoregulation, excretion and defense, the observed damages to the skin could be attributed to their sudden mortality in the UV exposure.     

Time-dependent effects of pentabrominated diphenyl ethers on gonadal hormone and genital system histology in male rats

The aim of this study was to examine the effects of pentabrominated diphenyl ethers (PBDE) on gonadal hormone levels and histology in male rats. Rats in treatment groups were orally gavaged with PBDE-99 at a dose of 120 mg?kg^?1 for 5, 15, 30, or 45 days, while controls received equal volume of corn oil. In the treated groups, changes were not found on day 5. On day 15, testicular weight increased, serum levels of estradiol (E₂) decreased, proliferation cell nuclear antigen (PCNA) positive expression was reduced, and sperms within the seminiferous tubules were damaged. On day 30, testicular weight was further increased, serum levels of testosterone (T) and E₂ decreased, PCNA positive expression was further reduced, some primary spermatocytes cells did not express, and seminiferous epithelium was degenerated. At 45 days, testicular weight decreased, levels of T, E₂ concentrations were lower, histopathologic examination revealed severe degeneration of seminiferous epithelium, and only a part of spermatogonial cells were expressed. The earliest alterations occurred at 15 days. PBDE-99 produced time-dependent reduction of gonadal hormone levels and degeneration of gonadal system histology.     

Time-dependent effects of pentabrominated diphenyl ether (PBDE) on thyroid hormones and histology in rats

In order to examine the time-dependent effects of pentabrominated diphenyl ether (BDE-99) on thyroid hormones levels and histological structure in rats, 4-week-old SD rats were divided into 10 groups randomly, according to their body weight. Rats in treatment groups were orally gavaged with BDE-99 at the dose of 60 mg kg^?1 for 10, 15, 20, 30 or 40 days, while rats in control group received equal volume of corn oil. Serum levels of thyroxine (FT4), triiodothyronine (FT3), and thyroid stimulating hormone (TSH) were measured by radioimmunoassay. Sections of thyroids were dyed with hematoxylin-eosin (HE) to detect any pathologically alterations. In BDE-99 treated groups, on day 10, changes in serum levels of FT4, FT3 and TSH were not found. On days 15 and 20, serum levels of FT4 and FT3 decreased, accompanied by increased levels of TSH. On days 30 and 40, serum levels of these hormones returned to control values. As for alterations in histology, on day 15, follicular epithelium of the thyroid were found to proliferate into two layers in BDE-99 treated rats. On day 20, in focal areas the two-layer follicular epithelia were observed to continuously proliferate into 3–4 layers of follicular epithelium, called hyperplasia plaques. On days 30 and 40, solid buds and secondary follicles to solid buds were detected. The earliest alteration of thyroid hormones in treated SD rats occurred at the duration of 10–15 days, with corresponding histopathologic changes. As the exposure time increased, the serum level of hormones and histopathology altered accordingly in a time-dependent manner.     

Sequential polyandry affords post-mating sexual selection in the mouths of cichlid females

Females mating with multiple males may obtain direct benefits such as nuptial gifts or paternal care or indirect (i.e. genetic) benefits resulting in higher-quality offspring. While direct benefits are easily identified, it is difficult to determine indirect benefits, and it is hence largely unclear how they are obtained. This is particularly true in species with external fertilisation, where females seem to have little control over fertilisation. In cichlids, most maternal mouthbrooders show sequential multiple mating, where females visit several males for egg deposition. Genetic data revealed that multiple paternity of eggs and young in the mouth of females is common, but behavioural data of female spawning decisions are missing. Here, we test four hypotheses to explain female multiple mating in the maternally mouthbrooding cichlid, Ophthalmotilapia ventralis: (1) fertilisation insurance, (2) genetic bet-hedging, (3) female choice and (4) ‘sperm shopping’ (i.e. induction of sperm competition resulting in sexually selected sperm). Detailed observations of spawning behaviour in the field combined with histological analyses of the male reproductive organs suggest that fertilisation insurance, genetic bet-hedging and pre-mating female choice are unlikely to explain the sequential female multiple mating in O. ventralis. Instead, cryptic female choice by sperm shopping, i.e. post-mating sexual selection, is most compatible with our data and might be the major ultimate cause of multiple mating in females of this species and of mouthbrooding cichlids with maternal care in general. Our study provides new insight into ultimate causes of sequential polyandry in species with external fertilisation, as hitherto post-mating sexual selection by cryptic female choice has been assumed to be incompatible with external fertilisation mechanisms except by components of the ovarian fluid.