Human transformation of ecosystems: Comparing protected and unprotected areas with natural baselines

Protected areas serve as reserves of biological diversity and conserve the naturalness of characteristic regional ecosystems. Numerous approaches have been applied to estimate the level of transformation of ecosystems and to compare trends inside and outside of protected areas. In this study, we apply aggregate indicators of anthropogenic pressures on ecosystems and biodiversity in a fine-scale spatial analysis to compare the level of human influence within protected and unprotected areas. The actual state of ecosystems is compared to a natural baseline that is intact or potential natural state. The results show that in a non-protected Central-European landscape, humans appropriate a considerable share of natural ecosystem productivity and carbon stocks, and significantly reduce natural biodiversity and ecosystem services. Human appropriation of net primary production reached more than 60% in total, humans reduced original biodiversity levels by 69%, and net carbon storage was considerably decreased by intensive types of land use. All three indicators significantly differed between protected areas and unprotected areas, suggesting that protected areas maintain higher biodiversity levels, store more carbon and are in total less influenced by human exploitation than average non-protected landscape. Furthermore, we bring evidence that human appropriation of net primary production is negatively related both to biodiversity and ecosystem services indicated by mean species abundance and net carbon storage at the national level. Our results contribute to the quantitative evidence of the impacts of anthropogenic transformation of natural ecosystems on the ecosystem condition, supporting the hypothesis that protected areas significantly reduce anthropogenic pressures and contribute to maintaining critical ecosystem services and biodiversity.     

互叶白千层油化学成分的研究

采用水蒸汽蒸馏收集互叶白千层芳香油,对该油进行ＧＣ／ＭＳ／ＤＳ定性分析及其总离于流图的面积归一化定量分析,鉴定出２５种化合物,其中含氧化合物６种,碳氢化合物１９种。直接影响该油商品价值的化学成分４－萜品醇含量约为１７％,桧樟脑含量约为２．４％。     

Polarity of meiotic gene conversion is 5′ to 3′ within the niaD gene of Aspergillus nidulans

We have examined polarity of meiotic gene conversion in the niiA-niaD gene cluster of Aspergillus nidulans in two-point crosses. The type and position of the mutations represented by the niaD alleles and the correlation between the relative frequency of gene conversion and the physical position of these mutations were determined. We show that polarity of meiotic gene conversion is 5 to 3 (transcribed strand) within the niaD gene. Additional crosses involving a niiA allele and a niaD allele show little polarity of gene conversion, which suggests that the recombination events leading to restoration of the niaD gene are initiated upstream of the coding region of the niaD gene but within the niiA-niaD gene cluster, possibly within the intergenic promoter region.     

Effects of fire season on flowering of forbs and shrubs in longleaf pine forests

Summary Effects of variation in fire season on flowering of forbs and shrubs were studied experimentally in two longleaf pine forest habitats in northern Florida, USA. Large, replicated plots were burned at different times of the year, and flowering on each plot was measured over the twelve months following fire. While fire season had little effect on the number of species flowering during the year following fire, fires during the growing season decreased average flowering duration per species and increased synchronization of peak flowering times within species relative to fires between growing seasons. Fires during the growing season also increased the dominance of fall flowering forbs and delayed peak fall flowering. Differences in flowering resulting from variation in fire season were related to seasonal changes in the morphology of clonal forbs, especially fall-flowering composites. Community level differences in flowering phenologies indicated that timing of fire relative to environmental cues that induced flowering was important in determining flowering synchrony among species within the ground cover of longleaf pine forests. Differences in fire season produced qualitatively similar effects on flowering phenologies in both habitats, indicating plant responses to variation in the timing of fires were not habitat specific.     

鳗鲡爱德华氏菌病的组织病理学研究

鳗鲡爱德华氏菌病病变性质为化脓性炎症。症理分型主要有两种：化脓性肝炎型、混合型。较早发生病变部位主要在肝脏,其化脓性病杜按病程分为初、中、晚期。肾脏、脾脏、胃粘膜、体表出现散在的脓肿、脓性溃疡、炎性血栓及血斑。此外,肝脏、肾脏实质细胞均出现变性和坏列、血管充血、出血等。本文详细报告了肝脏、脾脏、肾脏的超微结构变化并初步讨论了细胞、组织损伤的过程及细胞病理学、超微病理学意义。     

Role of the N-terminal region of the A chain in beta 1-bungarotoxin from the venom of Bungarus multicinctus (Taiwan-banded krait)

The N-terminal -amino groups of ₁-bungarotoxin (₁-Bgt) fromBungarus multicinctus venom were modified with trinitrobenzene sulfonic acid and the modified derivative was separated by high performance liquid chromatography. The trinitrophenylated (TNP) derivative contained two TNP groups at the -amino groups of A chain and B chain and showed a marked decrease in enzymatic activity. Methionine residues at positions 6 and 8 of the A chain were oxidized with chloramine T or cleaved with cyanogen bromide to remove the N-terminal octapeptide. Oxidation of methionine residues and removal of the N-terminal octapeptide caused a precipitous decrease in enzymatic activity, whereas antigenicity remained unchanged. The presence of dihexanoyllecithin influenced the interaction between ₁-Bgt and 8-antilinonaphthalene sulfonate (ANS) and revealed that ₁-Bgt consists of two types of ANS-binding sites, one at the substrate binding site of the A chain and the other might be at the B chain. The modified derivatives still retained their affinity for Ca²⁺ and ANS, indicating that the N-terminal region is not involved in Ca²⁺ and substrate binding. A fluorescence study revealed that the -amino group of the A chain was in the vicinity of substrate binding site and that the TNP -amino groups were in proximity to Trp-19 of the A chain. In addition, the study showed that the N-terminal region is important for stabilizing the architectural environment of Trp-19. The results, together with the proposal that Trp-19 of the A chain is involved in substrate binding, suggest that the N-terminal region of the A chain plays a crucial role in maintaining a functional active site for ₁-Bgt.     

The glycoprotein 71 of ecotropic Friend murine leukemia virus. Structure of the oligosaccharides linked to asparagine-12

The glycoprotein from Friend murine leukemia virus was digested with protease from Staphylococcus aureus V8. A glycopeptide comprising the N-terminal glycosylation site (Asn-12) was isolated from the mixture of fragments and analyzed by amino acid sequencing and methylation-capillary gas chromatography-mass spectrometry before and after treatment with sialidase from Vibrio cholerae. Asn-12 was thus found to be substituted by a family of partially sialylated, fucosylated, and intersected glycoprotein N-glycans of the hybrid type.     

Activity of the prothoracic gland and its sensitivity to prothoracicotropic hormone in the penultimate and last-larval instar of Bombyx mori

The time course of secretion of ecdysone in vitro by the prothoracic glands of Bombyx mori was studied through the penultimate and last-larval instars. Ecdysone was produced by the glands in high amounts by the penultimate instar at 72 and 84 h while the glands in the last instar exhibited a high activity over 4 days around the time of gut purge and thereafter. The glands in the penultimate instar produced ecdysone at a low level throughout the instar before the sharp peak of activity, when they became inactive and remained so for the first 3 days of the last instar after when they regained secretory activity. Sensitivity of the glands to prothoracicotropic hormone varied in accord with the changes in their secretory activity. Inactive glands were not stimulated by 22K-prothoracicotropic hormone. In addition, glands with maximal activity in the penultimate instar were insensitive to 22K-prothoracicotropic hormone. These results suggest that the prothoracic glands in the penultimate and last-instar larvae are physiologically different.     

Quantitative Analysis of Genera Endemic to China

Chinese flora with many endemic elements is highly important in the world’s flora. According to recent statistics there are about 196 genera of spermatophytes, being 6.5% of total Chinese genera. These endemic genera comprising 377 species belong to 68 families, among which the Gesneriaceae (28 genera), Umbelliferae (13), Compositae (13), Orchidaceae (12) and Labiatae (10) are predominant. The tropical type containing 24 families and 80 genera is dominant. After it follows the temperate type with 23 families and 50 genera. There are also 4 families endemic to China, i.e. Ginkgoaceae, Bretschneideraceae, Eucommiaceae and Davidiaceae. It shows that genera endemic to China are obviously related to the tropical and temperate flora in essence. The endemic monotypic genera (139) and endemic obligotypic genera (48) combined make up more than 95% of the total number of genera endemic to China. Phylogenetically more than half of them are ancient or primitive. The life forms of all endemic genera are also diverse. Herbs, especially perennial herbs, prevail with the proportion of about 62%, and trees and shrubs are the next, with 33%, and the rest are lianas. Based upon the calculated number of genera endemic to China in each province and the similarity coefficents between any two provinces, some conclusions may be drawn as follows: Yunnan and Sichuan Provinces combined are the distribution centre of genera endemic to China and may be their original or differentiation area, because numerous endemic genera, including various groups, exist in these two provinces. The second is Guizhou where there are 62 endemic genera. Others form a declining order, south China, central China and east China. But towards the north China endemic genera decrease gradually, and the Qinling Range is an important distributional limit. The largest simitarity coefficient, over 50%, appears between Shaanxi and Gansu probably because of the Qinling Range linking these two provinces. But between any other two provinces it is less than 30% and it is generaly larger between two south provinces than between two north provinces. These characteristics mentioned above are correlated with topography and climate, and they may be resulted from the diversification in geography and climatic influence for a long time.     

The concept of a changing receptor concentration: implications for the theory of drug action

Drugs are considered to produce their effects on biological tissues either by altering some physical property of cells or by interacting with specific cellular components, called receptors. Most drugs and endogenous neurotransmitters act on highly selective receptors located on the outer surface membrane of cells. These receptors were believed, until recently, to be stationary on the cell surface and to be present in unvarying numbers. Consequently, most early theorists modeled the drug-receptor interaction on the basis of stationary and static receptor molecules. The substantial advances in our understanding of drug action based on these models have partly justified this view. However, recent electron microscopic studies have revealed the presence of structures, including "coated" pits and vesicles, that appear to provide a mechanism by which cell surface receptors might be internalized in a process of endocytosis. The precise intracellular fate of these internalized receptors is unknown, but based on present understanding, it seems reasonable to believe that some are destroyed intracellularly whereas others are recycled to the cell surface. The importance of such processes to pharmacologic theory is a new awareness of a cellular pathway that is capable of internalizing drugs, receptors, or both. The implications of such a process to the theory of drug action extends to some unexplained drug phenomena such as down regulation, drug tolerance, tachyphyllaxis, and partial agonism. We present herein the theoretical framework for a model of drug action that incorporates the possibility of receptor internalization and subsequent degradation, recycling, or replacement.