Use of diethylstilbestrol and ethynylestradiol to feminize Nile tilapia Oreochromis niloticus (L.) in an outdoor environment

Two synthetic estrogens, diethylstilbestrol (DES) and ethynylestradiol (EE), were orally administered to 8.7 mm gonadally undifferentiated Oreochromis niloticus fry for a period of 28 days in an outdoor setting. Diethylstilbestrol was administered at doses of 100 mg, 200 mg, and 400 mg per kg diet. Ethynylestradiol was administered at 50 mg, 100 mg, and 200 mg per kg diet. One group received a non-hormone-treated feed. Hormone treatments produced significantly more (P < 0.05) than 50% females indicating that genotypic male fish were sex-reversed to phenotypic females. No rate of estrogen administration resulted in a 100% female population. Ethynylestradiol (EE) treatments resulted in 58–65% females, 32–35% males, and 3–9% hermaphrodites. Diethylstilbestrol (DES) treatments resulted in 60–80% females, 13–37% males, and 1–7% hermaphrodites. The DES 400 treatment was the most effective in altering phenotypic sex: 80% females, 13% males, 7% hermaphrodites.     

Extracellular polysaccharide of Nostoc commune (Cyanobacteria) inhibits fusion of membrane vesicles during desiccation

Cells of the cyanobacterium Nostoc commune secrete a complex, high molecular weight, extracellular polysaccharide (EPS) which accumulates to more than 60% of the dry weight of colonies. The EPS was purified from the clonal isolate N. commune DRH1. The midpoint of the membrane phase transition (T_m) of desiccated cells of N. commune CHEN was low (T_{m dry} = 8 °C) and was comparable to the T_m of rehydrated cells((T_m)_H20 = 6 °C). The EPS was not responsible for the depression of T_m. However, the EPS, at low concentrations, inhibited specifically the fusion of phosphatidylcholine membrane vesicles when they were dried in vitro at0% relative humidity (−400 MPa). Low concentrations of a trehalose:sucrose mixture, in a molar ratio which corresponded with that present in cells in vivo, together with small amounts of the EPS, were efficient in preventing leakage of carboxyfloroscein (CF) from membrane vesicles. Freeze-fracture electron microscopy resolved complex changes in the structure of the EPS and the outer membrane in response to rehydration of desiccated cells. The capacity of the EPS to prevent membrane fusion, the maintenance of a low T_{m dry} in desiccated cells, and the changes in rheological properties of the EPS in response to water availability, constitute what are likely important mechanisms for desiccation tolerance in this cyanobacterium. This revised version was published online in August 2006 with corrections to the Cover Date.     

Paraguayan pharmacies and the sale of pseudo-abortifacients

This study was conducted in 1985 in Asunción, Paraguay, 6 years after the closure of the state supported family planning services. Data from national surveys in 1977 and 1987 permit a comparison of sources of contraceptive supplies before and after the elimination of government support for family planning. The purchase of pseudo-abortifacients from private pharmacies was used as an indication of induced abortion. After the loss of government clinics, it is suggested that some women turned to pharmacists to obtain pseudo-abortifacients when faced with unwanted pregnancy. There is an indication of increased pseudo-abortifacient use, particularly among unmarried women and those from poorer neighbourhoods.     

Efficient fermentation of Pinus sp. acid hydrolysates by an ethanologenic strain of Escherichia coli.

Process conditions for the acid hydrolysis of pine hemicellulose and cellulose have been described which provide a biocompatible sugar solution. By using an improved strain of recombinant Escherichia coli, strain KO11, hydrolysates supplemented with yeast extract and tryptone nutrients were converted to ethanol with an efficiency of 85% to over 100% on the basis of monomer sugar content (approximately 72 g/liter) and with the production of 35 g of ethanol per liter in 48 h. In the process described, approximately 347 liters of ethanol could be produced per dry metric ton of lignocellulose.     

The predatory behaviour of Caranx melampygus (Pisces) in the channel environment of Aldabra Atoll (Indian Ocean)

Aspects of the predatory behaviour of free ranging Curanx melampygus have been examined in the shallow channel environment of Aldabra Atoll, Indian Ocean. Differences in the frequency of occurrence and number of fish hunting at two adjacent observation areas are described. The numbers of Caranx moving through the area appears to be influenced by tidal factors and possibly the abundance of prey and other environmental factors. The percentage offish hunting increases progressively throughout the day and is most commonly performed by solitary fish or small groups. While approximately equal numbers of Caranx move up or down stream significantly more fish engage in hunting activity when moving down stream which suggests the mechanical advantage of moving with the flow of water has advantages to the hunting fish. Several types of interspecific feeding association are described in which the Caranx is able to scavenge from others or to exploit the hunting methods of other species. More small Caranx form associations than do large Caranx . There is a relationship between the length of a hunting Caranx and the size and/or type of prey that makes an avoidance reaction to it. This relationship between different group sizes and the prey avoidance response is less clearly defined and it is suggested that whether hunting in groups or singly the final interaction is between a single predator and single prey. Ways by which group advantages may occur on grouped prey are described and are considered the result of independent individual action rather than group co-operation. Coastal observations indicate that Caranx use topographic features to shield their approach to areas of high prey density.     

Development of cell surface saccharides on embryonic pancreatic cells

Using a battery of seven lectin-ferritin conjugates as probes for cell surface glycoconjugates, we have studied the pattern of plasmalemmal differentiation of cells in the embryonic rat pancreas from day 15 in utero to the early postpartum stage. Our results indicate that differentiation of plasmalemmal glycoconjugates on acinar, endocrine, and centroacinar cells is temporally correlated with development and is unique for each cell type, as indicated by lectin-ferritin binding. Specifically, (a) expression of adult cell surface saccharide phenotype can be detected on presumptive acinar cells as early as 15 d in utero, as indicated by soybean agglutinin binding, and precedes development of intracellular organelles characteristic of mature acinar cells; (b) maturation of the plasmalemma of acinar cells is reached after intracellular cytodifferentiation is completed, as indicated by appearance of Con A and fucoselectin binding sites only at day 19 of development; conversely, maturation of the endocrine cell plasmalemma is accompanied by "loss" (masking) of ricinus communis II agglutinin receptors; and (c) binding sites for fucose lectins and for soybean agglutinin are absent on endocrine and centroacinar cells at all stages examined. We conclude that acinar, centroacinar, and endocrine cells develop from a common progenitor cell(s) whose plasmalemmal carbohydrate composition resembles most closely that of the adult centroacinar cell. Finally, appearance of acinar lumina beginning at approximately 17 d in utero is accompanied by differenetiation of apical and basolateral plasmalemmal domains of epithelial cells, as indicated by enhanced binding of several lectin-ferritin conjugates to the apical plasmalemmal, a pattern that persists from this stage through adult life.     

pH and Eh on Aldabra Atoll 2. Intertidal photosynthetic microbial communities showing zonation

The taxonomic status of Ephydatia subtilis (Weltner) remains undetermined. Despite extensive collecting in the type locality, Lake Kissimmee, Florida, the species was not found. Stratospongilla penneyi sp. nov. is described utilizing spicular diagnosis, cytochemistry, and scanning electron microscopy. Physicochemical data from the type locality are presented and specific threats to the existence of the species are determined.     

Cellular processing of pre-proparathyroid hormone involves rapid hydrolysis of the leader sequence.

The cellular synthesis of parathyroid hormone (PTH) involves two consecutive cleavages of NH2-terminal peptide sequences from a larger precursor, pre-proparathyroid hormone (Pre-ProPTH). The initial cleavage consists of the removal of an NH2-terminal leader sequence either during or shortly after biosynthesis of the polypeptide chain is complete. To determine the fate of the cleaved leader sequence, we prepared, by chemical synthesis, a peptide based on the known structure of the leader sequence of pre-proparathyroid hormone and used this peptide labeled with 125iodine as a marker to monitor the recovery of the putative cellular leader peptide during extraction and electrophoresis of [35S]methionine-labeled proteins from pulse-labeled parathyroid gland slices. Under conditions in which the recovery of the synthetic leader peptide was 50 to 70%, we found no detectable 35S-labeled product in the region of sodium dodecyl sulfate gels where the synthetic peptide migrates. In view of the known methionine content of pre-proparathyroid hormone and proparathyroid hormone (ProPTH), it would have been possible to detect endogenously labeled leader peptide if present in amounts equal to 0.05% of the amount of labeled ProPTH present in the tissues. These observations indicate that the cellular conversion of Pre-ProPTH to ProPTH involves a rapid hydrolysis of the leader peptide either during or immediately after its removal from the precursor.