Growth and vitality of epiphytic lichens

 We tested the hypothesis that changed microclimate at induced forest edges causes reduced growth of epiphytic lichens. Two foliose, green algal lichens were transplanted to the lower canopy of a mature Picea abies forest at six distances (2, 6.25, 12.5, 25, 50 and 100 m) from a clearcut. The biomass growth in Platismatia glauca (6.2% in 16 months) was 41% higher than in Lobaria pulmonaria (4.4%). We found no growth reduction near the forest edge. In contrast, the highest growth in both species occurred within 12 m from the edge. Further, fluorescence and chlorophyll measurements showed that lichen vitality was unaffected by distance from edge. The light intensity was 4.3 times higher at the edge than in the interior during the growing season, but there were only minor differences in air temperature and relative humidity. Monitoring of thallus water content revealed clear differences in both number and length of wetting and drying cycles. However, the total time with water content sufficient for photosynthetic activity was only slightly higher at the edge. The data thus indicate that our gradient in microclimate was too small to significantly affect lichen growth, and that lichens are largely metabolically inactive when large edge-interior contrasts in microclimate occur. Lichen response to forest edge microclimate results from intricate interactions among several biotic and abiotic factors. Linking data on lichen growth, microclimate and thallus water content with physiological measurements provides a framework for future studies of the mechanisms behind abiotic edge effects. Received: 15 April 1996 / Accepted: 21 June 1996     

Genetic analysis of Pycr1 and Pycr2 in mice

The final step in proline biosynthesis is catalyzed by three pyrroline-5-carboxylate reductases, PYCR1, PYCR2, and PYCR3, which convert pyrroline-5-carboxylate (P5C) to proline. Mutations in human PYCR1 and ALDH18A1 (P5C Synthetase) cause Cutis Laxa (CL), whereas mutations in PYCR2 cause hypomyelinating leukodystrophy 10 (HLD10). Here, we investigated the genetics of Pycr1 and Pycr2 in mice. A null allele of Pycr1 did not show integument or CL-related phenotypes. We also studied a novel chemically-induced mutation in Pycr2. Mice with recessive loss-of-function mutations in Pycr2 showed phenotypes consistent with neurological and neuromuscular disorders, including weight loss, kyphosis, and hind-limb clasping. The peripheral nervous system was largely unaffected, with only mild axonal atrophy in peripheral nerves. A severe loss of subcutaneous fat in Pycr2 mutant mice is reminiscent of a CL-like phenotype, but primary features such as elastin abnormalities were not observed. Aged Pycr2 mutant mice had reduced white blood cell counts and altered lipid metabolism, suggesting a generalized metabolic disorder. PYCR1 and -2 have similar enzymatic and cellular activities, and consistent with previous studies, both were localized in the mitochondria in fibroblasts. Both PYCR1 and -2 were able to complement the loss of Pro3, the yeast enzyme that converts P5C to proline, confirming their activity as P5C reductases. In mice, Pycr1; Pycr2 double mutants were sub-viable and unhealthy compared to either single mutant, indicating the genes are largely functionally redundant. Proline levels were not reduced, and precursors were not increased in serum from Pycr2 mutant mice or in lysates from skin fibroblast cultures, but placing Pycr2 mutant mice on a proline-free diet worsened the phenotype. Thus, Pycr1 and -2 have redundant functions in proline biosynthesis, and their loss makes proline a semi-essential amino acid. These findings have implications for understanding the genetics of CL and HLD10, and for modeling these disorders in mice.     

岱海流域土地利用动态模拟及生态系统服务价值测算

北方内陆湖泊面积萎缩严重,岱海作为典型的内陆湖之一,其面积变化尤为显著.为研究岱海湖面积变化及岱海流域生态系统服务价值(Esv)的动态趋势,本研究运用CA-Markov模型,基于1989-2018年6期的土地利用数据,预测2026年的土地利用状况,并采用当量因子法,对岱海流域ESV进行评估.结果 表明:岱海湖若不进行生...     

干扰素研究及应用进展

1957年,英国科学家Isaacs和Lindenmann利用鸡胚绒毛尿囊研究流感干扰现象时,发现一种能够干扰病毒繁殖的物质,称之为干扰素（IFN）,由于干扰素对许多疾病有很好的治疗作用,一直是医学领域研究的重要物质之一。现在干扰素已成功地用于肝炎、肿瘤治疗等方面。为了充分发挥干扰素的作用,人们稍用基因工程的方法来对干扰素的产量及功效进行改进,已达到更好的应用,因此基因工程干扰素越来越多地成了研究的重点。     

Temperament in Rhesus,Long‐Tailed,and Pigtailed Macaques Varies by Species and Sex

Temperament differs among individuals both within and between species. Evidence suggests that differences in temperament of group members may parallel differences in social behavior among groups or between species. Here, we compared temperament between three closely related species of monkey—rhesus (Macaca mulatta), long‐tailed (M. fascicularis), and pigtailed (M. nemestrina) macaques—using cage‐front behavioral observations of individually housed monkeys at a National Primate Research Center. Frequencies of 12 behaviors in 899 subjects were analyzed using a principal components analysis to identify temperament components. The analysis identified four components, which we interpreted as Sociability toward humans, Cautiousness, Aggressiveness, and Fearfulness. Species and sexes differed in their average scores on these components, even after controlling for differences in age and early‐life experiences. Our results suggest that rhesus macaques are especially aggressive and unsociable toward humans, long‐tailed macaques are more cautious and fearful, and pigtailed macaques are more sociable toward humans and less aggressive than the other species. Pigtailed males were notably more sociable than any other group. The differences observed are consistent with reported variation in these species’ social behaviors, as rhesus macaques generally engage in more social aggression and pigtailed macaques engage in more male–male affiliative behaviors. Differences in predation risks are among the socioecological factors that might make these species‐typical behaviors adaptive. Our results suggest that adaptive species‐level social differences may be encoded in individual‐level temperaments, which are manifested even outside of a social context. Am. J. Primatol. 75:303‐313, 2013. © 2012 Wiley Periodicals, Inc.     

Accurate and high resolution in situ hybridization analysis of gene expression in secondary stem tissues

Accurate in situ hybridization analysis in secondary stem tissues of plants has been hindered by specific characteristics of these tissues. First, secondary cell walls non-specifically bind probes used for in situ hybridization thus preventing gene expression analysis in the lignified regions of the stem, such as the xylem. Second, the mRNA in the cambial meristem and its recent derivatives are prone to inadequate fixation when conventional techniques are used. Here we describe an in situ hybridization technique which uses fast freezing and freeze substitution to cryoimmobilize the mRNA followed by embedding in a methacrylate resin for high-resolution analysis of gene expression. By using a transgenic poplar line harbouring rolC:uidA, rolC:iaaM, the gene expression pattern could be compared with histochemical GUS staining. This in situ hybridization technique results in superior preservation of cellular contents, retention of mRNA in all cell types in the poplar stem, a significant reduction of non-specific binding to secondary cell walls and a resolution not previously possible in secondary tissues. This technique will be particularly valuable for the expression analysis of genes involved in xylogenesis and wood formation.     

人热休克蛋白gp96基因的克隆及其在大肠杆菌中的表达与纯化

热休克蛋白gp96是热休克蛋白90家族成员,能够引起非特异性和特异性免疫反应。得到大量高纯度的蛋白质是研究开发gp96的关键。然而重组的gp96容易在E．coli中降解,并在一定条件下形成多聚体。实验先将人gp96基因克隆到pET-30a载体上并在E．coli Blstar中表达,再经过亲和层析、阴离子交换、分子筛分别纯化gp96。最终去掉了大部分的降解片段和多聚体,得到一定量的可溶性gp96,为进一步研究其结构和功能打下一定的基础。