Microsatellite-centromere mapping in Cynoglossus semilaevis using gynogenetic diploid families produced by the use of homologous and non-homologous sperm

Twenty-one microsatellite markers were studied in three meiogynogenetic families of Cynoglossus semilaevis gunther for centromere mapping using half-tetrad analysis. Among the 13 mapped loci, 10 were estimated to be located in the telomeric region, one in the centromeric region, and two in the intermediate region of the chromosome. This study provides a basis for constructing a linkage map of C. semilaevis .     

A case of monosomy 21

A new case of monosomy 21 was observed in a newborn male. Characteristic clinical features include: an antimongoloid eye slants, large and low set ears, flat nose bridge, hypoplastic nipples, cardiac anomalies, muscular hypotonia, retarded psychomotor development. The karyotypes of the parents were normal.     

Monitoring xanthan quality during fermentation by size exclusion chromatography

Summary Xanthan concentration and molecular weight distribution are determined by size exclusion chromatography in the fermentation medium after dilution and cell removal by centrifugation. The analysis is rapid enough for process control. During a batch fermentation, the average molecular weight is found to be in the range of 7.2–9.3·10⁶ g/mole and to run through a maximum.     

Replacement of arginine-171 and aspartate-453 in Streptomyces coelicolor malate synthase A by site-directed mutagenesis inactivates the enzyme

Malate synthase, a key enzyme of the glyoxylate cycle, catalyzes the condensation of glyoxylate and acetyl-CoA to yield malate and CoA. Escherichia coli is known to possess two forms of malate synthase, A and G respectively. The recent elucidation of the E. coli malate synthase G crystal structure suggested two residues, Arg338 and Asp631, are essential for catalysis. Multiple sequence alignment of 26 known malate synthase enzymes revealed that the two proposed sites are highly conserved, despite the low homologies between the two distinct forms of the enzyme (13-18%). The conservation of these residues in both forms of malate synthase suggests that they possess a similar catalytic strategy. Thus, despite the absence of a three-dimensional structure for malate synthase A, the significance of this enzyme in the primary metabolic pathway has prompted the investigation of the involvement of the corresponding residues, Arg171 and Asp453, in Streptomyces coelicolor malate synthase A by site-directed mutagenesis. Heterologous expression in E. coli followed by purification of the constructed mutant proteins, Arg171Leu and Asp453Ala, were performed and subsequent enzyme assays of the purified mutant proteins indicated a significant loss of catalytic activity, thus attesting to the need for the corresponding conserved residues to maintain malate synthase functionality.     

Fibril Formation of Bovine ��-Lactalbumin Is Inhibited by Glutathione

The current research is aimed at exploring the inhibitory effect of glutathione on fibril formation of an important four disulfide bond-containing whey protein, α-lactalbumin. Through numerous spectroscopic techniques and transmission electron microscopy, we found that the inhibition of amyloid formation of α-lactalbumin was dependent on the glutathione concentration and fibrillation was significantly attenuated in the presence of 5 mM glutathione. Moreover, the data from the measurements using 4,4′-dithiodipyridine reagent revealed that the treatment of α-lactalbumin with glutathione led to the exposure of sulfhydryl groups. Also, the observed inhibition of α-lactalbumin by glutathione was correlated with the reduction of disulfide bridges of protein. The results presented here suggest that the addition of food compatible reducing agent/dietary supplement such as glutathione would be useful for preventing the formation of milk protein fibrillar aggregates. The presence of these resulting aggregates can then, in turn, be used to modulate the key properties of food products such as protein beverage and yogurt.     

Direct shoot organogenesis and plant regeneration in Fortunella crassifolia

An efficient in vitro regeneration system in kumquats (Fortunella crassifolia Swingle) was established. Explant types and orientations, concentrations and combinations of plant growth regulators were evaluated for their influences on efficiency of plant regeneration. It was found that the optimum explant and its orientation was epicotyl planted vertically with upper part upward, and a shoot regeneration frequency of 1.48 shoots per explant was obtained on Murashige and Skoog (1962; MS) medium supplemented with 22.19 μM 6-benzyladenine (BA). A rooting percentage as high as 74 % was obtained on 1/2 MS supplemented with 0.54 μM 1-naphthaleneacetic acid (NAA), 9.29 μM kinetin (KN), and 0.5 g dm⁻³ activated charcoal.     

Neurotransmitter-related features of the retinal pigment epithelium

Various neurotransmitter-related biochemical features of the separated pigment epithelium and neural retina of the cow have been examined. The pigment epithelium contains high affinity binding sites for several pharmacological agents thought to attach to neurotransmitter receptor sites with a high degree of specificity. Thus, serotonergic, adrenergic and opiate receptors appear to be present in the pigment epithelium. Serotonin has also been detected in this region.Several neuropeptides were found in the pigment epithelium. Relatively large amounts of neurotensin and met-enkephalin were present, but substance P was not detected.     

A transposable element in diverse corn lines,Ubiquitous (Uq): allelism test

Since the discovery of the Uq transposable element system in the early 1980s, studies of Uq distribution have shown that Uq is pervasive in genetic stocks and corn populations including BSSS, the Illinois oil and protein lines, ‘Lancaster’, ‘Jarvis’ and several others. The assumption made was that Uq might have provided the variation that has contributed to maize breeding progress. Of the several inbreds tested in previous studies, only IaI159, one of the contributors to BSSS, contained an active Uq. The main question posed in our experiments was that of chromosomal location(s), or allelic relationships, of active Uq elements in diverse corn populations. Results showed that these Uq elements are allelic, linked or independent, though most found from corn populations show quite distant or independent linkage relationships with each other. The lack of a linear linkage map among these Uq elements may be interpreted to have resulted from transposition events and this might have led to the differentiated instability of an individual Uq element that was found to be variable. Other questions also discussed relate to the origin of Uq elements in corn populations and their role(s) in plant breeding.