Regeneration and structure of mixed conifer forests under single-tree harvest management in the western Bhutan Himalayas

We examined the regeneration and structure of mixed conifer forests under single-tree harvest management in western Bhutan. Sixteen 900 m² (30 m × 30 m) plots were sampled at four Forest Management Units (FMUs; Chamgang, Gidakom, Paro-Zonglela, and Haa-East) representing the forest type, including half the plots in single-tree harvest stands and half in unlogged stands. In addition, we solicited information on traditional forest management practices from informants using survey questionnaires and collected tree species data from felling records from respective local forest offices. Rural timber demand is concentrated on the removal of straight and well-formed bluepine trees for beams, planks, and scaffolding. Single-tree harvest, however, has not significantly altered stand structures from unlogged stands. Similarly, tree regeneration is not different when comparing single-tree harvest and unlogged stands, except at Chamgang FMU, where seedling densities were generally higher in harvested stands than in unlogged stands. These results indicate that single-tree harvest is not detrimental to regeneration and utilization of mixed conifer forests in western Bhutan.     

瑞士兽医实验室的生物安全管理

1 管理结构 　　设施管理组的主要任务:明确角色分配,明确传达信息,明确权限分配的安全管理方案.……     

Anatomopathological aspects of avian aspergillosis

Aspergillosis is a fungal disease caused by fungi of the genus Aspergillus, in particular A. fumigatus and A. flavus. This paper focuses on anatomopathological aspects resulting from a chronic infection from Aspergillus spp in the chicken (Gallus domesticus), in the herring gull (Larus cachinnans micaelli) and in the red-legged partridge (Alectoris rufa rufa). Microscopically, we observed some histological lesions that are related to the two typical forms of Aspergillosis: a deep nodular form, typical of organs with a non-aerated parenchyma, and a non-encapsulated superficial diffuse form typical of the serosae and the lung. The observed forms of aspergillosis have been found in animals raised in poor hygienic environmental conditions or malnourished animals (chicken); in wild birds from wildlife recovery centres (herring gull), which underwent some forms of stress, such as traumas, detention, starvation, extended antibiotic treatments; in game birds (red-legged partridge) used for restocking natural areas that had been negatively affected by such stressors as captivity in aviaries, containment and transport in cages, release in unsuitable environments and malnutrition. The observed anatomopathological and istopathological aspects can therefore be regarded as the outcome of a number of factors that have reduced the typical resistance of the species and impaired the efficiency of their immune systems.     

Evaluation of multi-satellite precipitation products for soil loss and sediment export modeling over eastern regions of the Koshi River Basin,Nepal

Journal of Soils and Sediments - Precipitation data are an important input variable for soil loss (SL) and sediment export (SE) modeling, although they are rarely available at fine spatial and...     

A mouse model of mitochondrial disease reveals germline selection against severe mtDNA mutations

The majority of mitochondrial DNA (mtDNA) mutations that cause human disease are mild to moderately deleterious, yet many random mtDNA mutations would be expected to be severe. To determine the fate of the more severe mtDNA mutations, we introduced mtDNAs containing two mutations that affect oxidative phosphorylation into the female mouse germ line. The severe ND6 mutation was selectively eliminated during oogenesis within four generations, whereas the milder COI mutation was retained throughout multiple generations even though the offspring consistently developed mitochondrial myopathy and cardiomyopathy. Thus, severe mtDNA mutations appear to be selectively eliminated from the female germ line, thereby minimizing their impact on population fitness.     

Effects of a tristearate-containing lipid and canola oil on plasma and tissue lipids in rats

Male Sprague-Dawley rats were fed semipurified diets containing 12% fat and 0.4% cholesterol for 4 wk. The fats were palm oil, a high-stearate fat and canola oil; each of the latter two fat sources was substituted for palm oil in 4% (w/w) increments (i.e, 4, 8 and 12%) thus yielding 3 stearate-containing, 3 canola-containing, and a 12% palm oil diet. Stearate-fed animals exhibited significantly decreased food efficiency ratios, plasma total cholesterol, and liver cholesterol whereas the substitution of canola for palm oil did not consistently alter these parameters. Liver fatty acids generally reflected the composition of the dietary fat sources with the exception of significantly higher arachidonate observed in the stearate-fed rats.     

Association between line per se and hybrid performance under excessive soil moisture stress in tropical maize (Zea mays L.)

Excessive moisture (EM) stress during the summer–rainy season is one of the major production constraints for maize (Zea mays L.) in large areas of South and South-East Asia. A key question in breeding for tolerance to excessive moisture is the extent to which the performance of maize hybrids can be predicted on the basis of per se performance of inbred lines under excessive moisture. We attempted to identify the relationship between morpho-physiological traits and grain yield measured on inbred parents and their single cross progenies under EM stress. Responses of various morpho-physiological traits, except days to 50% anthesis, differ significantly under normal versus EM stress. Superiority of hybrid progenies over parental inbred lines increased under EM stress, suggesting that hybrids were comparatively more tolerant to EM stress than inbred progenies. Across moisture regimes, all morpho-physiological traits of hybrids, except lodging and root porosity under normal moisture, were found to be positively and significantly correlated with mid-parent traits. Our data suggest that per se performance of lines was a relatively more important factor in determining hybrid performance under EM stress, while under optimum soil moisture conditions mid-parent heterosis was relatively more important than per se performance of mid-parent. Phenotypic correlation between hybrid and mid-parent yields showed a strong relationship under EM stress (r = 0.66^**). The relationship was statistically significant under normal moisture as well, though it was comparatively weak (r = 0.41^*). Our findings suggest that performance of hybrid progenies under excessive moisture can be predicted and improved to some extent on the basis of their inbred parents that have been systematically selected and improved for EM stress.     

Analysis of ATPase and succinic dehydrogenase in F1 hybrids of rice (Oryza sativa L.)

Summary Activities of ATPase and succinic dehydrogenase were assessed in three F₁ hybrids of rice and their parental lines during boot leaf stage, flowering, on 10th and 20th days after flowering. ATPase activity showed increase at the flowering and on 20th day after flowering. Succinic dehydrogenase activity continued to rise till 10th day after flowering and declined on 20th day after flowering. Hybrids with high yield were generally endowed with more positive heterosis for these two enzymes. Correlation coefficient of grain yield per panicle was significantly positive with ATPase activity at all the stages studied. Heterosis for ATPase activity might serve a reliable criterion for the selection of efficient F₁ combinations.