Intermittent exposure to aquatic pollutants: assessment,toxicity and sublethal responses in fish and invertebrates

Aquatic animals are often exposed to intermittent, variable poison concentrations during pollution incidents. However, current understanding of ecotoxicology has evolved primarily from continuous exposure studies. This review summarises the relatively dispersed toxicity literature on intermittent exposures. Methodologies used in existing continuous exposure toxicity tests may be adapted to intermittent regimes provided the exposure profile is known and “poison concentration” is defined to give toxicologically relevant lethality estimate. Such tests rely on assuming that continuous and intermittent exposures of equivalent dose have the same toxicity. This assumption is untrue for some chemicals. The toxicity of intermittent events may be assessed by correlating mortality with poison accumulation, biochemical, haematological or physiological response syndromes. Such bioassays can be performed without knowledge of the exposure profile, and are often sufficiently rapid to record short pollution events. Intermittent and continuous exposures of equivalent dose may not have the same toxicities. Intermittent exposures are less toxic than continuous events, but only when peak concentrations of pollutant are the same in each regime. Exceptionally, sulphuric acid, acid/Al and ammonia are much more toxic to fish when administered intermittently. Variations in intermittent exposure frequency or duration do not produce proportional changes in lethality, since apparently large changes in exposure dose may not significantly alter toxicity. The short-lived nature of intermittent exposures suggests that equilibriums in poison concentrations between the external environment and the body compartments of the test species are not achieved. The overall accumulation response depends particularly on the duration of peak concentrations and any “recovery periods” between multiple episodes relative to poison uptake and depuration rates respectively. Transient biochemical and physiological disturbances occur during intermittent exposures. Latent effects include reduced post-exposure growth and reproductive failure in the F₁ generation, or increased deformities in the F₂ generation of fish.     

Early transmembrane events in tumour cell responses observed by stopped-flow fluorometry

Early transmembrane events of tumour cells (mouse myeloma X5563 and lymphoma RDM4) after binding of a monoclonal antibody against mouse MHC antigen and a mitogenic lectin, Con A, were examined by stopped-flow fluorometry with 3 different fluorescent probes. The results showed that membrane fluidities of the cells increased first after binding of anti H-2Kk monoclonal antibody (11-4.1), then calcium was released from intracellular stores into the cytoplasma, and lastly calcium influx occurred from the external medium into the cytoplasma. While Con A only induced calcium influx from the external medium into the cytoplasma.     

对粘虫棉铃虫具有速杀活性的新有机磷杀虫剂T-751

T－751（0-甲基-o-苯基-s-正丙基硫代磷酸酯）对粘虫具有高速击倒活性,在所试验的5种杀虫剂中,T－751对粘虫击倒最快。在14·11mg／m2的剂量下,KT50值为5.32分钟,比杀螟松、喹噁磷分别高8倍和1倍。T－751对棉铃虫的击倒活性也是所试验的杀虫剂中最快的。T－751对粘虫具有胃毒和触杀活性,不具有内吸作用。     

定量测定储粮害虫胃毒作用的方法——混药薄片法

本实验制定一种定量测定储粮害虫胃毒作用的方法,命名为混药薄片法。通过试验验证饲料薄片对烟草甲Lasioderma serricorne(Fabricius)的幼虫成活率、发育历期、虫体重量、产卵量等生长发育无影响。在排除烯虫酯对烟草甲的触杀作用的前提下,将混有烯虫酯溶液的混药薄片作为饲料饲养烟草甲3龄幼虫,得到烯虫酯对烟草甲3龄幼虫的准确致死剂量为(0.46±0.03)μg。     

DETERMINATION OF THE RESISTANCE OF LOCUSTS TO DNC IN RELATION TO THEIR WEIGHT, AGE AND SEX

Experiments have shown that the resistance of adults of the desert locust ( Schistocerca gregaria ) and the African migratory locust ( Locusta migratoria migratorioides ) to DNC applied as a contact poison to the ventral surface of the abdomen is directly related to their body weight, irrespective of age or sex.
Varying the site of application of the insecticide had little effect on the susceptibility of the insects except when the dose was applied to the wings or femur, these being less effective sites of entry for the poison.
Increasing the post-treatment temperature from 25 to 36°C. had no noticeable effect on mortality, but the speed of action of the insecticide was much increased.     

Bait shyness of two gerbils, Tatera indica indica Hardwicke and Meriones hurrianae Jerdon

Two rodents, Tatera indica indica Hardwicke and Meriones hurrianae Jerdon, developed aversion to zinc phosphide after one day's exposure to a sublethal dose. The poison shyness persisted for at least 115 and 35 days, respectively.     

Characterization of cytoplasmic arginine-rich basic protein of Guerin epithelioma

Summary Arginine-rich basic protein from cytoplasma of Guerin epitheliomas has been isolated and characterized. It contains five amino acids: arginine, lysine, glycine, alanine and glutamic acid which make together 74 per cent of all amino acid residues. The protein has a cationic character with an isoelectric point of 8.2. No carbohydrate component was found in this protein. The significance of arginine-rich basic protein in the cytoplasma of Guerin epithelioma is discussed briefly.     

Role of male scent glands in improving poison bait acceptance in female rats,Rattus norvegicus

The poison (Zn3P2) bait mixed with preputial gland and cheek gland extract was highly effective as compared to poison bait mixed without the scent gland extract, in increasing the food consumption and mortality rate in rats. Among these two scent glands, preputial gland extract was more effective than cheek gland extract in increasing the bait acceptance. The scent gland extract mixed with poison bait was capable of improving the poison bait acceptance. A 10% concentration of scent gland extract was more effective than 5% concentration in acceptance of poison bait. The results suggest efficacy of scent gland in improving the poison bait acceptance.     

Effects of periodic administration ofNocardia rubra cell-wall skeleton on immunoglobulin production and B-cell-stimulatory factor activity in vitro in workers at a poison gas factory

Summary The former workers at the Okunojima poison gas factory (poison gas workers) are a high-risk group for malignant neoplasms and show abnormalities in cellular immunity. At the same time, poison gas workers often have chronic respiratory diseases, such as chronic bronchitis, and are highly susceptible to respiratory infections. To explore the possibility of immunological cancer prevention, we have periodically administered 200 µgNocardia rubra cell-wall skeleton (N-CWS) to poison gas workers once every 3 months since December 1978. During this period, we noted a significantly lower incidence of influenza among poison gas workers receiving N-CWS than in those not receiving the drug during the influenza epidemic. This finding suggested that the administration of N-CWS enhanced the resistance of these workers to infections. Therefore, periodical administration of N-CWS to poison gas workers was considered to enhance the reduced T-cell function of normalizing antibody production by stimulating the production of B-cell-stimulatory factor (BSF). In the present study, to clarify the mechanism of immunosuppression in the poison gas workers and to examine the effects of continual administration of N-CWS on this condition, we compared the immunoglobulin production and the proliferative and differentiative activities of B-cell-stimulatory factor (BSF) of peripheral blood mononuclear cells (PBMC), in poison gas workers treated or not treated with N-CWS. Comparisons were also made with age-matched healthy controls. In the untreated poison gas workers, immunoglobulin and BSF production of PBMC were reduced as compared with the control group. On the other hand, in the poison gas workers receiving N-CWS, immunoglobulin and BSF production of PBMC were restored nearly to the control level. These results show that in vitro antibody production in the poison gas workers was reduced and that a reduction in BSF production of T cells was one of its causes.     

嗜酸乳杆菌LB10.16及枯草芽孢杆菌BS7.29安全性评价

目的:评价枯草芽孢杆菌BS7.29和嗜酸乳杆菌LB10.16的安全性,为其应用研究提供技术支持。方法:本文通过对小鼠灌服、急性攻毒、腹腔注射、小鼠最大耐受剂量、急性攻毒等试验方法进行枯草芽孢杆菌BS7.29和嗜酸乳杆菌LB10.16的安全性研究。结果:1×108cfu/kg.bw的LB10.16和5×108cfu/kg.bw的BS7.29能够明显提高肠道推动力,改善小鼠肠道蠕动性。结论:两个菌种急性攻毒试验结果表明属于无毒物质,安全性比较高。     

Occupational illness and poison control centers. Referral patterns and service needs.

In a study of occupational illness reported to a regional poison control center and to gauge the center''s outreach and services, we did follow-up interviews of 301 case contacts over a 6-month period. We ascertained referral routes, reasons for contacting the poison control center, and awareness of the center''s function. For 122 cases a nonphysician was the initial poison control center contact. Of the nonphysician contacts, 41 had already consulted a health care provider and been referred to the poison control center for assistance. Of the 70 persons with exposure, only 21 had been aware before their exposures that poison control center services might include occupational chemical illness consultation. Physicians and nonphysicians expressed similar reasons for contacting the poison control center, with 118 of 301 identifying the need for an exposure hazard risk assessment. These data suggest that although those contacting a poison control center because of occupational illness include a variety of cases, they have many similar service needs.     

Relative investment in egg load and poison sac in fig wasps: Implications for physiological mechanisms underlying seed and wasp production in figs

Fig pollinating wasps and most non-pollinator wasps apply secretions from their poison sacs into oviposited flowers that appear necessary to the formation of the galls that their developing offspring consume. Thus, both eggs and poison sac secretions appear to be essential for wasp reproduction, but the relative investment in each is unknown. We measured relative investment in poison sac and egg production in pollinating and non-pollinating wasps associated with seven species of monoecious Panamanian figs representing both active and passive pollination syndromes. We then collected similar data for four fig hosts in China, where some wasp species in the genus Eupristina have lost the ability to pollinate (“cheaters”). All wasps examined possessed large poison sacs, and we found a strong positive correlation between poison sac size and absolute egg production. In the Panamanian species, the relative poison sac to egg investment was highest in the externally ovipositing non-pollinator wasps, followed by active pollinators, then by passive pollinators. Further, pollinator wasps of fig species with demonstrated host sanctions against “cheating” wasps showed higher investment in the poison sac than wasps of species without sanctions. In the Chinese samples, relative investment in the poison sac was indistinguishable between pollinators and “cheaters” associated with the same fig species. We suggest that higher relative investment in poison sac across fig wasp species reflects higher relative difficulty in initiating formation of galls and subsequently obtaining resources from the fig. We discuss the implications for the stability of the fig–wasp mutualism, and for the ability of non-pollinators to exploit this mutualism.     

A technique for determining the stomach poison effect of insecticides used against leaf-eating insects

Methods devised for feeding individual insects with leaf areas bearing known deposits of insecticides are described, and the problems associated with incomplete consumption of the treated leaf portions are discussed. An account is given of the difficulties of applying the technique to small insects and to those with erratic feeding habits.
Experimental data are given to illustrate the effects on insect resistance of the following: (i) rearing conditions, (ii) larval age and body weight, (iii) acute and chronic poisoning, (iv) the diluting effect of the leaf tissue consumed with the poison dose.
The dosage mortality curve for stomach poisons was found to be typically sigmoid: analysis of results by the method of probits (Bliss, 1934) therefore proved satisfactory. Using lead arsenate against fifth-instar larvae of Phlogophera meticulosa the ratio of weight increase to increase in median lethal dose was found to be constant.     

Estimating impacts of poison operations using mark-recapture analysis: hihi (

Hihi (Notiomystis cincta) were reintroduced to Mokoia Island, Lake Rotorua, New Zealand, in September 1994, and two years later there was an aerial drop of brodifacoum cereal pellets aimed to eradicate mice (Mus musculus). Using Program MARK, we analyzed data from resighting surveys to assess whether hihi had lower than normal survival in the 6-week interval following the drop. The resighting data were collected on a regular basis over a 3-year period, from 1994-97, allowing us to control for yearly and seasonal variation in resighting and survival probabilities. We initially established that the Cormack-Jolly- Seber model had a good fit to the data and could therefore be used as the global model for our analysis. We then compared a range of simpler candidate models, some of which included a poison effect (an unusual survival rate for the interval after the poison drop). Under the best model (that with the lowest AIC), the survival probability was constant over time and there was no poison effect. The estimated survival probability for the 6 weeks after the poison drop was 0.95, which is slightly higher than the value of 0.89 expected based on pre- and post- poison intervals. The approximate 95% confidence interval for the probability of a bird dying due to poison ranged from -0.17 (i.e., a decrease in mortality rate due to the poison) to +0.04. We therefore concluded that the poison caused at most a negligible increase in mortality, and that mark-recapture analysis on resighting data provided a powerful method for assessing the impact of the poison drop. We discuss the relative costs and benefits of radio tagging versus resighting surveys of banded birds for estimating impacts of poison operations. For species with relatively high resighting rates, such as hihi, analysis of resighting surveys is a much more reliable and cost-efficient methodology.     

钉螺肝脏的光镜和电镜观察

对湖北钉螺指名亚种（Oncomelania hupensis hupensis)肝脏的显微和超微结构作了较详细的研究。肝腺管壁由单层柱状上皮细胞构成。上皮细胞内,粗面内质网呈多层次板层状,主要分布于核周围,线粒体有椭圆、杆状两种形态,核上万有高尔基复合体并多有溶酶体出现。胞质中分泌颗粒分为四种,细胞基部的颗粒电子密度很高,中部有巨大颗粒,近细胞游离端的大、中、小分泌颗粒可连同胞质一起排放入管腔。在肝脏间质中的网状细胞多呈三角形状,有血细胞团和毛细血管腔构造。     

The pp60c-src in retinal pigment epithelium and its modulation by vasoactive intestinal peptide.

The pp60c-src is present at high level in differentiated retinal pigment epithelium (RPE) in culture. Immunofluorescence microscopy using GD11 (anti-pp60c-src) shows intense staining in the plasma membrane, especially at the cell-cell junctions, and diffuse staining in the cytoplasma. Western blot analysis shows that the majority of the GD11-reactive molecules is localized in the membrane. The pp60c-src does not translocate between membrane and cytoplasma when the RPE was reacted with vasoactive intestinal peptide (VIP), which is previously shown to stimulate phosphorylation of the pp60c-src in the membranes (Biochem. Biophys. Res. Commun. 174, 452-8, 1991). Here, VIP modulation is shown to alter the reactivity of pp60c-src with a monoclonal anti-phosphotyrosine antibody.     

The stimulation of the delayed hypersensitivity reaction by the venom of the blunt-nosed viper Vipera lebetina and by its liposomal form]

Native poison of middleasia viper Vipera lebetina has been included into liposomes in order to get an effective preparation for immunotherapy. The preparation reduces the risk of complications taking place during the use of traditional methods. The immunomodulating action of the liposomal form of viper poison has been investigated on the model of reaction of hypersensitivity of delayed type. Together with the stimulation of functional activity T-cells, the absence of suppressive and toxic actions while using the liposomal preparation of poison has been discovered. It is suggested that the observed stimulating effect in connection with immune reactions is due to synergism of action of components of poison liposomal form and activation of T-cells and macrophage, taking part in immune response to the antigenic stimulus.     

Ultramicroscopic observations on glomic tumors]

Ultra microscopic study of three glomic tumours established the presence in these of myoepithelial cells with a cytoplasma rich in fibrils and deprived of secretory granules. These typical cells are very different of these of chimioreceptors of chromophile system.     

Cytogenetic assays of chemical clastogens using mammalian cells in culture.

A protocol is described for cytogenetic assays of chemical mutagens using mammalian cells in vitro. The system employs continuous drug treatment (3 concentrations) for up to 8 h and recovery-cell populations after pulse treatments with a high dose. Both direct fixation (for recording spindle anomalies in anaphase) and colcemid-hypotonic fixation (for reading metaphase chromosome aberrations) are used in order to estimate the effects of an agent as a mitotic poison and as a clastogen respectively. Some DNA intercalating dyes (acridine orange, quinacrine mustard, neutral red) were found to be highly clastogenic whereas others (quinacrine dihydrochloride, 33258 Hoechst) are not.