Influence of Some Physicochemical Parameters on Artemia Biomass and Cyst Production in Some Thalassohaline Aquatic Environments in the Colombian Caribbean

Abstract. –From July 1998 to June 2000 four thalassohaline aquatic environments along the Colombian Caribbean coast (Manaure, Galerazamba, Salina Cero, and Tayrona) were surveyed monthly to determine the influence of salinity, percent 0₂ saturation, pH, temperature, and nutrients (NO₂^-, NO₃^- and PO₄^-3) on Artemia (Crustacean, Anostracan) biomass production and cyst production potential. The effects of the regularly measured physicochemical parameters on biomass and cyst production potential were analyzed using univariate analysis of variance (SPSS VI 0.0). The influence of physicochemical parameters on biomass production was not significant (P > 0.05). In contrast, there was a significant interaction (P< 0.05) of salinity, percent 0₂ saturation, and nitrate (used as a proxy for chlorophyll a) on cyst production potential. In addition, for all four locations nitrate levels were directly proportional to salinity. This might be explained by the fact that in saltworks numerous organisms are trapped and slowly die as salinity increases progressively in the evaporating basins; thus, organic matter accumulates and decomposes. Consequently, the concentration of the nitrogenous compounds, first nitrite and later nitrate, increases through time as salinity increases. Moreover, decreasing nitrate levels seem to increase cyst production potential; thus supporting the notion that when insufficient food is available cyst production increases.     

Estimation of air quality degradation due to Saharan dust at Nouakchott, Mauritania, from horizontal visibility data

It is now irrefutable that air pollution caused by large amounts of Total Suspended Particulates (TSP) and respiratory particulates or Particulate Matter less than 10 μm in aerodynamic diameter (PM₁₀) has numerous undesired consequences on human health. Air quality degradation far from the African continent, in the US and in Europe, caused by high concentrations of African dust, is seen as a major threat even though most of these countries are very distant from the Sahara. Surprisingly, no estimates of TSP or PM₁₀ levels near the Saharan dust source are available. Based on horizontal visibility observations which are reduced by the presence of dust in the atmosphere, TSP and PM₁₀ levels are estimated throughout the year 2000 at Nouakchott-Airport, Mauritania, using relations found in the literature. It appears that concentrations of particles are significant both in terms magnitude and frequency, as the 24-hour PM₁₀ thresholds established by the US EPA National Ambient Air Quality Standards and the EU Limits Values for Air Quality were exceeded 86 and 137 times, respectively. The average annual concentration is far above air quality standards and estimated at 159 μg m^?3 for TSP and 108 μg m^?3 for PM₁₀. These very high particulate levels are likely to represent an important public health hazard and should be considered as a major environmental risk.     

Genetic diversity in ecotypes of Tunisian date-palm (Phoenix dactylifera L.) assessed by AFLP markers

Summary

Amplified fragment length polymorphisms (AFLP) were used successfully to survey genetic diversity in 40 ecotypes of date-palm (Phoenix dactylifera L.) collected from oases in Tunisia. Six primer pairs were screened to assess their ability to detect polymorphism in this tree crop. As a result, a total of 428 AFLPs have been generated and used to estimate genetic distances which ranged from 0.07 – 0.63. A large, and typically continuous, range of genetic diversity characterises Tunisian date-palm germplasm. In addition, the UPGMA dendrogram derived from these data exhibited two clusterings of ecotypes independent of their geographic origin or the sex of the trees. These data corroborate the hypothesis of the origin of date-palm domestication being in Mesopotamia. Moreover, taking into account the high percentage of polymorphic bands, together with their resolving power (Rp), all the primer pairs tested contributed to the discrimination of date-palm genotypes, suggesting that the AFLP method is efficient in assessing genetic diversity in this crop. The data are discussed in relation to the use of AFLP molecular markers in the management and improvement of date-palm.     

响应面法优化红小豆中总酚的提取

以红小豆为原料,采用有机溶剂浸提法,对煮制后的红小豆中抗氧化物质进行提取。以总酚含量为指标,通过单因素和Box-Behnken试验得到了最佳煮制参数为：煮制时间为9 min,液料比为20∶1,压力为0.075 MPa,在此条件下进行提取,得到煮制红小豆中总酚含量为0.732 8 mg.g-1。     

Effect of saline water irrigation and manure application on the available water content, soil salinity, and growth of wheat

Good water management combined with appropriate soil management is necessary for sustainable crop production in drylands. A pot culture experiment was conducted using sand dune soil under greenhouse conditions to evaluate the response of wheat (Triticum aestivum L.) to the application of farmyard manure (FYM) or poultry manure (PM), and irrigation with water at two salinity levels (0.11 and 2.0 dS m⁻¹) and two irrigation intervals (daily and every second day). The manure was applied at a rate of 20 Mg ha⁻¹. The soil water content, measured 1 h before every irrigation, showed that soil treated with PM retained more water than that treated with FYM, while the control (no manure) contained the least water. FYM treatment resulted in 78 and 21% higher dry matter yield compared to the control and PM treatments, respectively, under daily irrigation using good-quality water. The increase was 29 and 55%, respectively, when saline water was used for daily irrigation. A similar trend was observed with the alternate day irrigation treatment; FYM gave the highest dry matter yield. The number of tillers and plant height showed that FYM was better than PM, which in turn was better than the control under irrigation with good-quality water regardless of the irrigation interval. When water of the highest salinity was used for irrigation, FYM was still always the best, but the control was now better than the PM treatment. The electrical conductivity of the soil measured at the end of the experiment was slightly higher with PM, as compared to the FYM and control treatments. A significant interaction between irrigation water quality and manure application was observed, affecting plant growth. PM aggravated the adverse affect of saline water on plant growth by increasing soil salinity.     

热带普通小球藻生长过程中色素质量浓度和颜色值变化及相关性分析

该文基于CIE-L*a*b*颜色分析系统,采用全自动分光测色仪对热带普通小球藻(Chlorella vulgaris)生长过程中的颜色值变化进行监测,同时测定其细胞密度及色素的质量浓度变化并进行相关分析。结果显示,热带普通小球藻生长过程中细胞密度分为接种期、快速生长期、稳定期和衰亡期4个阶段,绿色素和黄色素质量浓度和颜色参数值黄度值(b*)、色差值(△E)和饱和度(C)均呈增加趋势,而颜色参数值明度值(L*)、红度值(a*)、相角(H°)呈降低趋势;颜色参数值与细胞密度、色素质量浓度具有较强的相关性,线性回归模型拟合度较高,在快速生长期尤为显著,其中b*和△E可作为较佳的指示指标。通过量化热带普通小球藻生长过程中的颜色参数变化,建立非接触性数量及质量动态变化预测模型,可快速准确预测,为提高养殖过程中精细操作及效率提供理论基础。     

NompC TRP channel required for vertebrate sensory hair cell mechanotransduction

The senses of hearing and balance in vertebrates rely on the sensory hair cells (HCs) of the inner ear. The central element of the HC's transduction apparatus is a mechanically gated ion channel of unknown identity. Here we report that the zebrafish ortholog of Drosophila no mechanoreceptor potential C (nompC), which encodes a transient receptor potential (TRP) channel, is critical for HC mechanotransduction. In zebrafish larvae, nompC is selectively expressed in sensory HCs. Morpholino-mediated removal of nompC function eliminated transduction-dependent endocytosis and electrical responses in HCs, resulting in larval deafness and imbalance. These observations indicate that nompC encodes a vertebrate HC mechanotransduction channel.