Lectin‐Binding Pattern in Ovarian Structures of Rats with Experimental Polycystic Ovaries

Numerous experimental models in different species have been developed for the study of polycystic ovarian syndrome. In this study, we used a model of induction of polycystic ovaries (PO) in rats by exposure to constant light to study the distribution and variations of glycosylated residues present in the different ovarian structures. Seven biotinylated lectins were used (Con‐A, WGA, DBA, SBA, PNA, RCA and UEA‐I) on tissue sections, and detection was performed using the streptavidin/peroxidase method. In tissue sections was observed an increase in affinity for Con‐A in the granulosa and theca interna of growing follicles and cysts in animals with PO in relation to the control group. Follicular cysts showed higher affinity for WGA and RCA‐I which growing follicles in the same group, and there was a decrease in affinity for PNA in the cysts in relation to the growth of follicles in both groups. Atretic follicles in both groups showed greater labelling with lectins PNA, SBA and RCA‐I in relation to healthy follicles. It could also be noted that the zona pellucida of cystic follicles lost the affinity for the lectin Con‐A. There was no staining on follicles in any category with the lectins DBA and UEA‐I, although it was staining in the corpus luteum (control group) and in the mesothelium and interstitial glands of both groups with DBA. These observations probably reflect changes in the glycosaminoglycans present in the different ovarian compartments or in the glycosylation of cellular components essential for proper follicular dynamics.     

ECONOMIC FEASIBILITY OF SMALL-SCALE BLACK-LIPPED PEARL OYSTER (PINCTADA MARGARETIFERA) PEARL FARMING IN THE CENTRAL PACIFIC

ABSTRACT

This work provides an analysis of the economic feasibility of one of many small-scale aquaculture operations being considered, black pearl oyster farms, as one type of supplemental economic activity for outer island communities in the Central Pacific. Specifically, projections of financial performance of a small-scale 25,000 seeded pearl oyster farm using the Tahitian long-line method are being conducted. Estimates of initial capital investment and annual operating costs are being formulated, an annual cash flow and enterprise budget are being developed. Results show that initial capital investment is $202,076. Annual operating expenses are $293,726 during full operation. The largest costs contributing to annual operating expenses are seeding (46%), labor including farm owner's opportunity cost (24%), and depreciation (9%). The base model presented in this work suggests profitability over a 20-year horizon.

Net returns over a 20-year farm horizon based on an 8% discount rate indicate a positive NPV of $ 102945. Sensitivity analysis on profit due to the variability of market price, survival, and cost of seed and other inputs are conducted and results presented.     

海原试区土壤资源及其培肥改良

从分析区域气候条件、地貌基础、成土母质、植被和人类活动等成土因素入手，探讨了海原试区土壤形成的基本过程、类型划分和分布规律，论述了主要土壤的性态特征，提出区域土壤培肥改良的关键措施。     

Constant Light Exposure Causes Dissociation in Gonadotrophin Secretion and Inhibits Partially Neuroendocrine Differentiation of Leydig Cells in Adult Rats

The objective of this work was to study the changes that occur in the Leydig cells of rats exposed to continuous light. The laboratory rat is considered a non-photoperiodic species because exposure to short photoperiod has little or no effect on the reproductive status. However, exposure of adult female rats to constant light induces polycystic ovaries, indicating that extreme changes in the photoperiod affect the reproductive function seriously. Adult male rats were placed under continuous light conditions for a duration of 15 weeks. After this period, the animals were killed and testicles were dissected and processed by routine histologic protocols. Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) serum levels were determined by radioimmunoassay (RIA). The visualization of antigens was achieved by the streptavidin-peroxidase immunohistochemical method. Antibodies against chromogranin A, S-100 protein, P substance, synaptofisin, neurofilament protein-200, gliofibrillary acidic protein and neurone-specific enolase were used. The mean LH serum concentration was significantly lower, while the mean FSH level was significantly higher in treated animals. The expression of S-100, NSE, CrA, SP and SYN was significantly lower in treated animals. In conclusion, the constant light exposure acting directly at the pituitary level decreases LH secretion. The increased FSH secretion may be due to a partial reduction of the negative androgen feedback in the pituitary gland. Moreover, the constant light exposure affects the expression of some immunomarkers in Leydig cells, possibly because of the changes found in the gonadotrophin level and feedback mechanism.     

A new phenolic glucoside from the leaves of Heliciopsis lobata

A new phenolic glucoside ester, 6'-E-(2'-methyl-2'-butenoyl) arbutin (1), was isolated from the leaves of Heliciopsis lobata. Its structure was elucidated by spectral analysis.     

Long-term agroecosystem experiments: assessing agricultural sustainability and global change

Long-term agroecosystem experiments can be defined as large-scale field experiments more than 20 years old that study crop production, nutrient cycling, and environmental impacts of agriculture. They provide a resource for evaluating biological, biogeochemical, and environmental dimensions of agricultural sustainability; for predicting future global changes; and for validating model competence and performance. A systematic assessment is needed to determine the merits of all known experiments and to identify any that may exist in tropical and subtropical environments. The establishment of an international network to coordinate data collection and link sites would facilitate more precise prediction of agroecosystem sustainability and future global change.     

构建与社会主义新农村建设相适应的农村金融体系

当前,社会主义新农村建设,一方面带来了越来越大的农村金融需求,另一方面也凸显了农村金融需求与供给之间的诸多矛盾。本文建议,要从建立多层次、竞争性的农村金融机构体系,分类指导农村信用社改革,推动农村民间金融合法发展,加大政府对农村金融的扶持力度等方面着手,构建与社会主义新农村建设相适应的农村金融体系。