Biotransformation of phenylpyruvic acid to phenyllactic acid by growing and resting cells of a <Emphasis Type="Italic">Lactobacillus</Emphasis> sp.

Phenyllactic acid (PLA) is a novel antimicrobial compound derived from phenylalanine (Phe). Lactobacillus sp. SK007, having high PLA-producing ability, was isolated from Chinese traditional pickles. When 6.1 mM phenylpyruvic acid (PPA) was used to replace Phe as substrate at the same concentration, PLA production increased 14-fold and the fermentation time decreased from 72 h to 24 h with growing cells. With resting cells, however, 6.8 mM PLA could be obtained as optimal yield using the following conditions: 12 mM PPA, 55 mM glucose, pH 7.5, 35°C and 4 h.     

A mutant hemolysin with lower biological activity produced by a mutant Vibrio parahaemolyticus

Abstract A mutant toxin (m-TDH) of thermostable direct hemolysin (Vp-TDH) of Vibrio parahaemolyticus w was isolated from the culture of a strain of this organism mutagenized with N -methyl- N '-nitro- N -nitrosoguanidine. Although the m-TDH had a molecular structure similar to the native Vp-TDH, the m-TDH retained only about 7% residual hemolytic activity of the native toxin. Furthermore, other biological activities of m-TDH, such as lethality in mice and enterotoxicity in rabbit ileal loops, were also weakened. The m-TDH was immunologically indistinguishable from the native Vp-TDH. These results suggest that the m-TDH is only slightly different in structure from the native Vp-TDH. Also, the mutagenized site in m-TDH, which is not immunogenic, seems to be involved in expressing not only hemolytic activity but also lethal and enterotoxic activity.     

Longevity determined by developmental arrest genes in Caenorhabditis elegans

The antagonistic pleiotropy theory of aging proposes that aging takes place because natural selection favors genes that confer benefit early on life at the cost of deterioration later in life. This theory predicts that genes that impact development would play a key role in shaping adult lifespan. To better understand the link between development and adult lifespan, we examined the genes previously known to be essential for development. From a pool of 57 genes that cause developmental arrest after inhibition using RNA interference, we have identified 24 genes that extend lifespan in Caenorhabditis elegans when inactivated during adulthood. Many of these genes are involved in regulation of mRNA translation and mitochondrial functions. Genetic epistasis experiments indicate that the mechanisms of lifespan extension by inactivating the identified genes may be different from those of the insulin/insulin-like growth factor 1 (IGF-1) and dietary restriction pathways. Inhibition of many of these genes also results in increased stress resistance and decreased fecundity, suggesting that they may mediate the trade-offs between somatic maintenance and reproduction. We have isolated novel lifespan-extension genes, which may help understand the intrinsic link between organism development and adult lifespan.     

Tagging of a maize gene involved in kernel development by an activated Uq transposable element

Summary A quiescent Uq transposable element has been activated in a maize plant treated with 5-aza-2-deoxycyti-dine. This activated Uq cosegregates with a heritable dominant miniature (Mn) kernel phenotype, indicating its physical association with a maize miniature locus (Mn:: Uq). The Mn:: Uq mutant is dominant in producing a miniature seed phenotype of variable size and in reducing seedling vigor in the early growth stage. Genetic experiments indicate that the Mn:: Uq mutant also affects the activity of the male gametophyte, whereby pollen germination is inhibited, thus lacking pollen tube growth resulting in the male nontransmissibility of this mutant. Proof for the Uq element in this mutant is derived by its ability to transactivate the standard a-ruq reporter allele to yield spotted aleurone tissue. However, the Mn:: Uq mutant does not transactivate a normally Uq-responsive c-ruq allele, suggesting a structural difference between the two ruq receptors at the A1 and C1 loci. It is anticipated that cloning of the Uq transposable element would facilitate the molecular cloning and characterization of the maize miniature gene.Journal Paper No. J-13425 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa 50011, USA, Project No. 2850     

Phylogeny of Snub-Nosed Monkeys Inferred from Mitochondrial DNA,Cytochrome B,and 12S rRNA Sequences

Snub-nosed monkeys (Rhinopithecus spp.) are confined to isolated mountainous regions in China and North Vietnam. Their systematic classification and phylogenetic relationship has been controversial. The structures of mitochondrial DNA cytochrome b and 12S rRNA show that the 4 species of Rhinopithecus are quite different from other colobines. It is reasonable to regard them as an independent genus, as determined by external features, morphometric characters and behavior. However, whether or not there should be a subdivision between the Vietnamese and Chinese species at the subgeneric level remains to be clarified; more evidence from a large range of Asian colobine species is needed. The Guizhou species, Rhinopithecus brelichi, is a valid species, which is more closely related to Pygathrix than the other species ( R. roxellana, R. bieti and R. avunculus) are. Results also indicate that 3 species—Rhinopithecus roxellana, R. bieti and R. avunculus—might have diverged from R. brelichi, but the phylogenetic relationship of R. avunculus is not clear.     

Genetic diversity within Oryza rufipogon germplasms preserved in Chinese field gene banks of wild rice as revealed by microsatellite markers

Nineteen microsatellite markers were employed to evaluate the genetic diversity of 92 accessions of common wild rice Oryza rufipogon Griff., which represent a significant portion of the distribution range from field gene banks of China. In comparison, a total of 57 varieties from most of the rice growing areas in China were also analyzed. The microsatellite analysis revealed a considerable amount of genetic diversity resided within the preserved wild rice germplasms. In all, the nineteen microsatellites revealed 328 alleles. The number of alleles per locus varied widely among these markers, ranging from 6 at RM242 to 30 at RM206. A comparison of the genetic parameters showed that wild rice strains preserved in the field gene banks (na = 17.27; R _S = 15.66; H _S = 0.86; H _T = 0.852; H _O = 0.307) possess much higher genetic diversity than cultivated rice varieties (na = 8.27; R _S = 8.14; H _S = 0.75; H _T = 0.758; H _O = 0.051). A total of 196 alleles detected in the wild rice could not be found in cultivated rice, suggesting that about 60% of the alleles of wild rice might be lost during the process of rice domestication. This result shows that these ex situ preserved wild rice strains are of great importance for the discovery and utilization of novel genes in the future rice breeding practices. Considerably abundant genetic variability detected within the studied wild rice germplasms could be comparable to that previously found in a wide sampling of 47 natural populations (na = 16.17; H _S = 0.67; H _O = 0.229), demonstrating that developing field gene banks of wild rice is a necessary and efficient way for preserving genetic diversity of wild rice resources. To determine minimum microsatellites that could distinguish these wild rice accessions, the phylogenetic trees constructed by means of the combinations of different microsatellites suggested that the five highly polymorphic microsatellites could clearly identify these samples. High polymorphisms of rice microsatellite loci and their great resolving power will be particularly helpful for germplasm evaluation and evolutionary studies for better strengthening the conservation and utilization of genetic diversity of wild rice in the field gene banks.     

Effect of red mold rice on antifatigue and exercise-related changes in lipid peroxidation in endurance exercise

This study evaluated the effect of red mold rice supplementation on antifatigue and exercise-related changes in lipid peroxidation of male adult Wistar rats through swimming exercise. Thirty 16-week-old rats were studied by dividing them into three groups (ten for each group). Other than the control group (CD), the other two groups were divided into a high-dose (HD) treatment group (5 g red mold rice/kg body weight for the HD group), and a low-dose (LD) group (1 g red mold rice/kg body weight for the LD group). Swimming endurance tests were conducted after 28 days of red mold rice supplementation, and the result showed that the treatment group showed a higher exercise time (CD, 78.0±6.4; LD, 104.2±9.6; and HD, 129.4±10.9 min; p<0.05) and a higher blood glucose concentration (CD, 76.67±8.08; LD, 111.34±8.50; and HD, 117.67±11.06 mg/dl; p<0.05) than the CD. Moreover, the blood lactate (CD, 45.00±0.90; LD, 31.41±1.80; and HD, 28.89±1.62 mg/dl; p<0.05), blood urea nitrogen (CD, 21.87±0.75; LD, 20.33±0.83; and HD, 20.53±1.09 mg/dl; p<0.05), and hemoglobin (CD, 14.20±0.21; LD, 13.70±0.55; and HD, 13.28±0.35 g/dl; p<0.05) were also significantly lower than those of the CD. Besides, the result suggested that the red mold rice supplementation may decrease the contribution of exercise-induced oxidative stress and improve the physiological condition of the rats.     

Involvement of central GABAergic neurons in basal and diurnal changes of tuberoinfundibular dopaminergic neuronal activity and prolactin secretion

Central administration of gamma-aminobutyric acid (GABA) has been shown to stimulate the secretion of prolactin (PRL). Whether GABA acts via dopamine, the major PRL-inhibiting hormone, and which GABA receptor type(s) is involved have not been ascertained. Both GABA(A) and GABA(B) receptor agonists and/or antagonists were administered centrally in this study and their effects on both basal and diurnal changes of tuberoinfundibular dopaminergic (TIDA) neuronal activity were determined by measuring the concentration of 3,4-dihydroxyphenylacetic acid (DOPAC) in the median eminence (ME). Serum PRL level was determined by RIA. Ovariectomized, estrogen-primed Sprague-Dawley rats implanted with intracerebroventricular (icv) cannulae were used. Muscimol (1 ng/3 microl/rat, icv), a GABA(A) receptor agonist, but not baclofen (1-100 ng/3 microl/rat, icv), a GABA(B) receptor agonist, injected in the morning significantly lowered and elevated ME DOPAC and serum PRL levels, respectively at 15 and 30 min. Lower and higher doses of muscimol were not effective. The effects of muscimol could also be prevented by co-administration of bicuculline (0.1-10 ng/3 microl, icv), a GABA(A) receptor antagonist. When bicuculline (10-500 ng/3 microl, icv) was given in the afternoon (at 1500 h), it significantly reversed the lowered ME DOPAC level in the afternoon and prevented the concurrent PRL surge. We conclude that endogenous GABA acting through GABA(A) receptors may play a significant role in the control of basal and diurnal changes of TIDA neuronal activity, and in turn, PRL secretion.