中国柯属5种资源植物潜在地理分布及其对气候变化的响应

利用最大墒模型和地理信息系统软件对柯属（Lithocarpus）5种资源植物在我国的适宜分布区进行了定量预测,并对未来不同气候情景下其分布区的变化进行了分析。结果显示：木姜叶柯（L.litseifolius（Hance）Chun.）在我国秦岭淮河以南广泛分布,短尾柯（L.brevicaudatus（Skan）Hay.）主要分布在我国亚热带中东部区域;木姜叶柯在未来气候（2061-2080年）RCP2.6、RCP8.5两种情景下适生区面积分别减少了5.1%和3.0%,而短尾柯却分别增加了0.5%和1.5%。白柯（L.dealbatus（Hook.f.et Thoms.ex DC.）Rehd.）适宜区主要分布在云南北部、四川南部,烟斗柯（L.corneus（Lour.）Rehd.）主要分布在两广省份的南亚热带地区。白柯和烟斗柯在RCP2.6情景下适生区面积分别减少了12.1%和17.8%,在RCP8.5情景下分别减少了3.5%和15.9%,这两个种的适宜区面积减少较多。厚斗柯（L.elizabethae（Tutch.）Rehd.）主要分布于广西,在两种情景下适宜区面积分别增加了7.3%和6.3%。研究结果表明,由于分布区存在差异,同属不同物种的未来分布对气候变化的响应不同。     

浙江省水鳖科植物的种类与分布

浙江省有水鳖科植物5属8种,均属淡水种类,其中无尾水筛、有尾水筛和密齿苦草为浙江分布新记录。在水平分布上,水筛属分布局限于浙江东南部,苦草属则分布于浙江大部分地区而未见于浙江南部。在垂直分布上,水筛属的种数和分布量,在海拔600米以下,随海拔增高而增加,再向上又有减少的趋势;其余各属的种数和分布量则随海拔增高而减少。它们的分布主要受各自适宜的生境在水平和垂直带的不同分布所制约。浙江水鳖科植物区系与我国亚热带各省区尤其是相邻省的关系十分密切。     

山西朔县种子植物区系及其生态经济意义

朔县(现朔州市朔城区)植物种属相对丰富,具有维管束植物938种,隶属于420属,105科。其植物区系主要起源于古北大陆;种子植物属的地理成分复杂多样,以温带成分占绝对优势,具有典型的温带草原性质;与相邻地区植物区系的比较分析表明,联系最为密切的是蒙古草原植物区系,其次是黄土高原植物区系。该县植物资源利用应采取的对策是:既要合理开发利用,又要加强物种的保护。     

Tissue distribution,metabolism, and elimination of perfluorooctanoic acid in male and female rats

The elimination, tissue distribution, and metabolism of [1-¹⁴C]perfluorooctanoic acid (PFOA) was examined in male and female rats for 28 days after a single ip dose (9.4 μmol/kg, 4 mg/kg). A sex difference in urinary elimination of PFOA-derived ¹⁴C was observed. Female rats eliminated PFOA-derived radioactivity rapidly in the urine with 91% of the dose being excreted in the first 24 hr. In the same period, male rats eliminated only 6% of the administered ¹⁴C in the urine. The sex-related difference in urinary elimination resulted in the observed difference in the whole-body elimination half-life (t_1/2) of PFOA in males (t_1/2 = 15 days) and females (t_1/2 < 1 day). Analysis of PFOA-derived ¹⁴C in tissues showed that the liver and plasma of male rats and the liver, plasma, and kidney of female rats were the primary tissues of distribution. The relatively high concentration of PFOA in the male liver was further examined using an in situ nonrecirculating liver perfusion technique. It was shown that 11% of the PFOA infused was extracted by the liver in a single pass. The ability of the liver to eliminate PFOA into bile was examined in rats whose renal pedicles were ligated to alleviate sex differences in the urinary excretion of PFOA. In a 6-hr period following IP administration of PFOA, there was no apparent difference in biliary excretion, where both males and females eliminated less than 1% of the PFOA dose via this route. We hypothesized that the sex difference in the persistence of PFOA was due to a more rapid formation of a PFOA-containing lipid (i.e., a PFOA-containing mono-, di-, or triacylglycerol, cholesteryl ester, methyl ester, or phospholipid) in the male rat. Also, the increased urinary elimination of PFOA in females may have been due to increased metabolism to a PFOA-glucuronide or sulfate ester. However, no evidence that PFOA is conjugated to form a persistent hybrid lipid was obtained, nor were polar metabolites of PFOA in urine or bile detected. In addition, daily urinary excretion of fluoride in male and female rats before or after PFOA treatment were similar, suggesting that the parent compound is not defluorinated. Thus, the more rapid elimination of PFOA from female rats is not due to formation of a PFOA metabolite.     

中国灵芝科真菌资源与分布

中国灵芝科资源十分丰富。许多种类具有重要的经济价值。现在已知灵芝种类有88种。本文概述了灵芝对国民经济的重要性,中国古籍中有关灵芝的记载,灵芝的化学成分与制剂,灵芝的临床应用,灵芝的人工培养,灵芝的生态习性与分布。     

The effects of selective fish predation on the horizontal distribution of pelagic Cladocera in a southern French reservoir

A four-year study showed a clear seasonal succession of species within the cladoceran community of the large, oligotrophic Sainte-Croix reservoir (S.E. France). Diaphanosoma brachyurum and Ceriodaphnia pulchella were strictly limited to the warm stratified period (July to October), whereas Bosmina longirostris and Bosmina coregoni were dominant during spring and autumn. Daphnia longispina was the only species to occur throughout the year with higher densities in spring.In spring and late autumn, the discharge of the inflowing river Verdon was high and the abundance of all species showed a gradient over the whole lake with lower densities close to the inflow. During the stratified period, water inflow was very low and species showed different patterns. Densities of the small form Ceriodaphnia pulchella were similar all along the long axis of the lake, whereas Daphnia densities were significantly higher near the dam. The distribution pattern of Diaphanosoma, an intermediate-sized species, showed similar trends to that of Daphnia. The only planktivorous fish in the pelagic zone, the bleak (Alburnus alburnus), fed mostly on large-bodied species (> 1.0 mm) and was more abundant close to the inflow current. A comparison between the length frequency distributions of cladocera upstream and downstream provided a clear demonstration of the effects of size-selective predation on prey populations. Finally, the interactions between spatial heterogeneity and long-term development of the zooplankton community and the indirect effects of predation are discussed.     

Identification, Development, and Regional Distribution of Thymidylate Synthetase in Adult Rabbit Brain

Abstract: The development and regional distribution of thymidylate synthetase (TS) (EC 2.1.1.45) in rabbit brain were determined. After optimization of the assay for brain, TS activity in brain was measured by a nonspecific (³H₂O release) and specific method. The specific method involved the conversion of [6-³H]deoxyuridine monophosphate (dUMP) to [³H]thymidine phosphate and the subsequent identification of [³H]thymidine. The specific activity of the enzyme in whole brain of newborn rabbits declined from 10.35 ± 1.17 units/mg protein to 0.71 ± 0.09 units/mg protein at 10–12 weeks of age. Two-year-old rabbits had 0.81 ± 0.04 units/mg protein. The decline in specific activity with age was not due to an inhibitor of TS activity or a change in the K_m for dUMP. The K_m for dUMP of the unpurified enzyme in the brains of both 10-day-old and young adult rabbits was 0.8 μ m . In young adult rabbits (3 months) the specific activity of TS was similar in the various regions of the brain tested except for the cerebellum, which had 40% higher specific activity than the whole brain. The results show that TS is widely distributed in adult rabbit brain, and, although the activity declines with age, it stabilizes at adult levels at 3 months of age.     

Rat Brain 3-Hydroxy-3-Methylglutaryl-CoA Reductase: Subcellular Distribution and Cold Lability

Abstract: Data are provided indicating that the rat brain 3-hydroxy-3-methyl-glutaryl-CoA reductase is similar to the enzyme from other tissues as far as diurnal rythmicity, cold lability and half-life measurements at 0°C are concerned. The enzyme activity in the brain decreased with age of the animals. Subcellular fractionation studies demonstrate that while 77% of the activity was associated with the microsomal fraction, 19% of the enzyme activity was recovered in the mitochondrial fraction. The possible function of such a mitochondrially located 3-hydroxy-3-methylglutaryl-CoA reductase in rat brain is discussed.     

Factors influencing the distributional abundance of two trophic guilds of Peruvian cricetid rodents

The distributional abundance of 13 species of southern Peruvian rodents is significantly correlated with altitude and patterns of vegetation but vegetation is a better predictor than altitude. Coincidental reversals in the altitudinal trends of both vegetation and rodents demonstrate that rodents are responding to vegetation patterns. Abundance and diversity of rodents are greatest around 4000 m elevation which coincides with the region of greatest vegetational abundance and seasonally heavy rainfall.
The rodent communities consist of two separate feeding guilds, omnivores and insectivores and these guilds show distinctly different distributional patterns. Insectivorous species are strongly associated with the zone of seasonally heavy rainfall (4000 m) whereas omnivorous rodents are relatively abundant over a broader spectrum of elevations and habitats. In a previous study of these same communities, we showed a correspondence between rodent morphology and their diets. This study reveals a correspondence between distributional abundance of the various species and their diets. We conclude that the distributional abundance of southern Peruvian rodents is related to the physiological constraints imposed by altitude (climate) and the distributional abundance of food resources.     

Changes in spatial distribution pattern during the larval stage of the fall webworm,Hyphantria cunea drury (Lepidoptera: Arctiidae)

Summary The changes in spatial distribution pattern during larval stage of the fall webworm,Hyphantria cunea were quantitatively investigated in the field experimental populations. The female adult deposits eggs as a cluster and the hatchlings make a compact colonial-web. In this period, the all-or-none type mortality which is characteristic in gregarious insect species was occasionary recognized before spinning a compact colonial-web. Once making a compact colonial-web, the larvae feed the leaves in the colonial-web up to about 5th instar. In this period, the movement of larvae occurred due to the local food shortage in a colonial-web and the expansion of colonial-web. As the larvae developed, the colonial-web was separated into several small groups. These larvae began to disperse about 5th instar. In this period, the local food shortage seems to be an important trigger for the larval dispersal. The mean concentration of larvae on leaves abruptly decreased, and finally the larvae became solitary at the 6th or 7th instars. The dispersal process in later larval stage is not necessarily due to the complete food shortage. The dispersal prior to the occurrence of food shortage may be a safety mechanism to protect the larvae from the food shortage.