Freemartinism among singleton bovine females born from multiple embryo transfer

Heterosexual chimerism among singleton females produced by multiple nonsexed embryo transfer (MNET singleton females) was investigated using chromosome typing and PCR (polymerase chain reaction)-amplification of male-specific DNA (msDNA). Of the 22 animals tested, 21 were classified as normal by both methods (i.e., showing no male cells among 100 metaphase spreads in chromosome typing and being msDNA negative in PCR). No morphological abnormalities of the genital organs were observed among 19 MNET single females. One MNET singleton female was, however, classified as a freemartin by PCR (male-specific DNA positive), but it was classified as normal cytogenetically. This individual probably had a low degree of heterosexual chimerism, and it seems that the chimerism derived from MNET was difficult to diagnose by chromosome typing, although it was detectable by PCR. The genital organs of this individual (15-mo-old Aberdeen Angus) were normal in form (both external and internal) and size. However, a very small structure, resembling seminiferous tubule, was found in the left ovary. It may be concluded that most MNET singleton females are expected to have normal reproductive function.     

Use of filamentous cyanobacteria for biodegradation of organic pollutants

Volume 61, no. 1, p. 234: the corresponding author footnote should read as follows: * Corresponding author. Present address: Center for Risk Management, Oak Ridge National Laboratory, Oak Ridge, TN 37830. Phone: (615) 241-6013. Fax: (615) 574-9887. [This corrects the article on p. 234 in vol. 61.].     

Conservation breeding as a tool for saving animal species from extinction

For nearly 3000 taxa of birds and mammals, conservation breeding may be the only possible way to avoid extinction. Today, less than 100 of these taxa have self-sustaining captive populations, and even fewer have been selected for reintroduction programmes. However, recent developments in our theoretical understanding of conservation breeding, as well as in its practical application, and global organization, raise hopes for the future.     

Production of a lipopeptide antibiotic, surfactin, by recombinant Bacillus subtilis in solid state fermentation

Production of a lipopeptide antibiotic, surfactin, in solid state fermentation (SSF) on soybean curd residue, Okara, as a solid substrate was carried out using Bacillus subtilis MI113 with a recombinant plasmid pC112, which contains lpa-14, a gene related to surfactin production cloned at our laboratory from a wild-type surfactin producer, B. subtilis RB14. The optimal moisture content and temperature for the production of surfactin were 82% and 37 degrees C, respectively. The amount of surfactin produced by MI113 (pC112) was as high as 2.0 g/kg wet weight, which was eight times as high as that of the original B. subtilis RB14 at the optimal temperature for surfactin production, 30 degrees C. Although the stability of the plasmid showed a similar pattern in both SSF and submerged fermentation (SMF), production of surfactin in SSF was 4-5 times more efficient than in SMF. (c) 1995 John Wiley & Sons, Inc.     

Preparation of immobilized enzyme with high activity using affinity tag based on proteins A and G

Affinity tag AG consisting of immunoglobulin G (lgG)-binding domains of protein A from Staphylococcus aureus (EDABC) and those of protein G from Streptococcus strain G148 (C2C3) were used to facilitate immobilization of beta-galactosidase (betagal) from Escherichia coli. Poly(methylmethacrylate/N-isopropylacrylamide/methacrylic acid) [P(MMA/NIPAM/MAA)] and poly(styrene/N-isopropylacrylamide/methacrylic acid) [P(St/NIPAM/MAA)] latex particles, which show thermosensitivity, were used as support materals to prepare affinity adsorbents. Human gamma-globulin (HgammaGb), whose major fraction is lgG, was used as an affinity ligand and was covalently immobilized onto the both latex particles by the carbodiimide method under various conditions. A fusion protein, AGbetagal, was immobilized at pH 7.3 by the specific binding of affinity tag to these affinity adsorbents. The amount of adsorbed AGbetagal per unit amount of immobilized HgammaGb, namely, efficiency of ligand utilization, was strongly affected by the type of latex particles and pH value for HgammaGb immobilization. The efficiency of ligand utilization was maximum in the affinity adsorbents prepared at pH 6.0 to 7.0, and that in the HgammaGb-P(MMA/NIPAM/MAA) latex particles was high. This result could be explained by the conformation and orientation of immobilized HgammaGb molecules. Immobilized AGbetagal retained approximately 75% of its activity in solution and the binding is stable enough to allow repeated use. These results clearly demonstrate that combination of the affinity tag AG and the affinity adsorbents, based on the thermosensitive latex particles, offers a simple and widely applicable method for preparation of immobilized enzyme with high activity. (c) 1995 John Wiley & Sons, Inc.     

Apical targeting in polarized epithelial cells: There's more afloat than rafts

Most metazoan cells are 'polarized'. A crucial aspect of this polarization is that the plasma membrane is divided into two or more domains with different protein and lipid compositions or example, the apical and basolateral domains of epithelial cells or the axonal and somatodendritic domains of neurons. This polarity is established and maintained by highly specific vesicular membrane transport in the biosynthetic, endocytic and transcytotic pathways. Two important concepts, the 'SNARE' and the 'raft' hypotheses, have been developed that together promise at least a partial understanding of the underlying general mechanisms that ensure the necessary specificity of these pathways.