神经毒素BMAA在淡水池塘水体中的健康风险及调控技术

为掌握中国常见淡水养殖生态系统中神经毒素β-N-甲氨基-L-丙氨酸BMAA的污染水平,文章选取典型淡水养殖池塘的水体、底泥及6种水产品(河蚬、铜锈环棱螺、日本沼虾、中华绒螯蟹、青鱼和鲫)进行BMAA的含量检测,在此基础上开展BMAA对人体的健康风险评估.同时采用L-半胱氨酸修饰后的氧化石墨烯为载体,结合化感物质"没食子...     

The rate of oxygen consumption during embryogenesis of Lymnaea stagnalis (Gastropoda)

We studied the rate of oxygen consumption by the Lymnaea stagnalis embryos. The rate of oxygen consumption increased consistently during embryogenesis. The volume specific rate of oxygen consumption increased initially from the early cleavage stages until the gastrula stage and then decreased gradually to the eclosion of snails. There are three periods in embryogenesis of L. stagnalis, which differ in the coefficients of allometric dependence between the rate of oxygen consumption and volume of embryos: (1) early embryogenesis, when the increase in the rate of oxygen consumption is not accompanied by the growth of volume of the embryos; (2) larval period (trochophore and veliger stages; exponential coefficient k = 0.514), and (3) postlarval period (exponential coefficient k = 0.206).     

Pelagostrobilidium wilberti n. sp. (Oligotrichea, Choreotrichida): morphology and morphogenesis

Morphology, infraciliature, morphogenetic features, and some ecological data for Pelagostrobilidium wilberti n. sp. are described. This new species was collected from a temporary pond in Magdalena, Buenos Aires province, Argentina, which was sampled monthly from August 2003 to July 2005. The species was found in autumn and winter. Observations were made in vivo and after staining with protargol. Pelagostrobilidium wilberti n. sp. measures 63-84 x 42-49 microm in vivo and is conical in shape, with a posterior spine-like cytoplasmic process. It possesses 6 somatic kineties, with kinety 2 sinistrally curved and shorter than the others. The oral apparatus is composed of 25-32 external and two internal membranelles. The macronucleus is horseshoe-shaped and located beneath the oral apparatus; two or three spherical micronuclei lie dorsally. There is a posterior contractile vacuole. Morphogenesis is hypo-apokinetal and begins dorsally between the curved kinety 2 and kinety 3. After the discovery of this new species, the diagnosis of the genus Pelagostrobilidium was amended.     

Adaptive phenotypic plasticity and genetics of larval life histories in two Rana temporaria populations

Phenotypic plasticity provides means for adapting to environmental unpredictability. In terms of accelerated development in the face of pond-drying risk, phenotypic plasticity has been demonstrated in many amphibian species, but two issues of evolutionary interest remain unexplored. First, the heritable basis of plastic responses is poorly established. Second, it is not known whether interpopulational differences in capacity to respond to pond-drying risk exist, although such differences, when matched with differences in desiccation risk would provide strong evidence for local adaptation. We investigated sources of within- and among-population variation in plastic responses to simulated pond-drying risk (three desiccation treatments) in two Rana temporaria populations originating from contrasting environments: (1) high desiccation risk with weak seasonal time constraint (southern population); and (2) low desiccation risk with severe seasonal time constraint (northern population). The larvae originating from the environment with high desiccation risk responded adaptively to the fast decreasing water treatment by accelerating their development and metamorphosing earlier, but this was not the case in the larvae originating from the environment with low desiccation risk. In both populations, metamorphic size was smaller in the high-desiccation-risk treatment, but the effect was larger in the southern population. Significant additive genetic variation in development rate was found in the northern and was nearly significant in the southern population, but there was no evidence for genetic variation in plasticity for development rates in either of the populations. No genetic variation for plasticity was found either in size at metamorphosis or growth rate. All metamorphic traits were heritable, and additive genetic variances were generally somewhat higher in the southern population, although significantly so in only one trait. Dominance variances were also significant in three of four traits, but the populations did not differ. Maternal effects in metamorphic traits were generally weak in both populations. Within-environment phenotypic correlations between larval period and metamorphic size were positive and genetic correlations negative in both populations. These results suggest that adaptive phenotypic plasticity is not a species-specific fixed trait, but evolution of interpopulational differences in plastic responses are possible, although heritability of plasticity appears to be low. The lack of adaptive response to desiccation risk in northern larvae is consistent with the interpretation that selection imposed by shorter growing season has favored rapid development in north (approximately 8% faster development in north as compared to south) or a minimum metamorphic size at the expense of phenotypic plasticity.     

Microbial interactions responsible for dissolved DNA production in a hypereutrophic pond

Concentration of dissolved DNA, microbial biomass, and consumption of bacteria by heterotrophic nanoflagellates (HNF) and ciliates were examined in a hypereutrophic pond for over 7 months to elucidate the main factors which influenced the release of dissolved DNA. Changes in concentration of dissolved DNA correlated well with both abundance of ciliates ( r = 0.788, p < 0.01) and rotifers ( r = 0.738, p < 0.01). A significant correlation was also found between dissolved DNA concentration and ciliate community ingestion rates ( r = 0.668, p <0.01). These results suggest that consumption of bacteria by ciliates is an important reason for the release of dissolved DNA. This revised version was published online in July 2006 with corrections to the Cover Date.     

PROTOPERIDINIUM BELIZEANUM SP. NOV. (DINOPHYCEAE) FROM MANATEE CAY,BELIZE, CENTRAL AMERICA1

A new marine heterotrophic dinoflagellate species, Protoperidinium belizeanum sp. nov., from a coral reef‐mangrove pond was identified from scanning electron micrographs. Recognition of this new species was based on unique features of the thecal morphology, which included cell size and shape, presence of short and wide postcingular plates, sulcal architecture, antapical spines, and intricate thecal plate patterns of ridged hexagonal depressions. The thecal plate formula is as follows: Po, X, 4′, 3a, 7″, 4C (3+t), 6S, 5?, 2″″. Species association of P. be‐lizeanum sp. nov. within the genus Protoperidinium, its habitat, and associated dinoflagellates species are discussed.     

在主施氯化铵的混养池塘中鲢,鳙生长的研究

以鲢、鳙为主养鱼类的混养池塘中,在各种条件基本相同的情况下,设计了４种以氯化铵为氮源、１种以碳铵和尿素为氮源、１种以有机肥为肥源的追肥处理,旨在查明６种追肥处理对鲢、鳙生长的影响。试验结果表明：氯化铵能促进鲢、鳙快速生长;Ｎ与Ｐ＿２Ｏ＿５,的比为２：１时生长最佳。分析讨论了６种追肥处理池塘中鲢、鳙在不同养殖阶段的生长特点,并提出了进一步增产的措施。     

Secondary productivity and energy flow in a tropical pond

Monthly changes in density and biomass of a Pila globosa population were estimated in the littoral area of the pond Idumban. Mean density of active snail was 10.4, equivalent to 76 g dry weight/m² during 1973 and 6.5, equivalent to 45 g/m² during 1974. Total population size of the snail decreased from 9.2 × 10⁶ individuals, equivalent to 6.5 ton during 1973 to 6.3 × 10⁶ snails, equivalent to 4.4 ton during 1974. The period from December to May represented the time of abundance and active growth. Mortality assessed from marking and recapture as well as from monthly changes in population density, averaged to 2.7 snails/m²/month or 20% of the density. Growth estimated by marking and recapture suggested that the snail required a period of over 4 years to attain a body (wet) weight of 35 g. Laboratory experiments revealed that young (<4 g), intermediate (4 g><24 g) and old (>24 g) P. globosa grew at the rate of 4.0, 1.5 and 0.3 mg dry weight/g live weight/day. Using these values and the size-wise population density data, net productivity of the snail was estimated as 74 and 40 g/m²/year in 1973 and 74, respectively. The snail exhibited an efficiency of 70% for absorption and 10% for conversion. Using these values, it was further possible to estimate rates of feeding and absorption for the population. Consumption amounted to 1039 g/m² in 1973 and 560 g/m² in 1974. The efficiencies of exploitation, gross and net productions were 21, 7 and 10%, respectively; ecological efficiency amounted to 1.4% only.     

Benthos of a seasonally-astatic, saline, soda lake in Mexico

The benthic macroinvertebrate community (BMC) of Lake Tecuitlapa Sur, central Mexico, was monitored to determine the structure of the community (i.e. species composition, richness, abundance and biomass), throughout an annual cycle. Tecuitlapa Sur is shallow, seasonally-astatic, warm, mesosaline, and soda-alkaline. The physical, chemical and biological variables were determined monthly for a yearly cycle. Tecuitlapa Sur displayed a seasonal patterns of dilution (June–August) and concentration (September–November) phases. Salinity and pH were the most important parameters explaining environmental variance. The BMC consisted of two species: Culicoides occidentalis sonorensis (Diptera: Ceratopogonidae) and Tanypus Apelopia sp. (Diptera: Chironomidae). C. occidentalis was the most important species both numerically and in biomass (95%). Annual density (mean ± sd) of C. occidentalis (1141082 ± 2765879 ind. m^–2, n = 120) was notably higher than other reported for other saline water bodies. However, the mean annual density of T. Apelopia (6782 ± 8310 ind. m^–2, n = 120) was similar to other saline lakes. Seasonal abundance and biomass dynamics of the BMC showed an increasing trend until October (T. Apelopia) and November (C. occidentalis), when massive emergence occurred, just before the lake dried out. Contrary to most temporal waters, Tecuitlapa Sur did not show taxonomic or trophic succession. C. occidentalis, a transient detritivore, dominated over T. Apelopia, a resident predator during the wet period.