Sex pheromones in maleMelittobia parasitic wasps: Female response to conspecific and congeneric males of 3 species

Presented a choice between conspecific males and 2 congeneric males, virgin females ofMelittobia australica andM. digitata chose conspecific males disproportionately more often, whereasM. femorata females distributed themselves evenly among the choices. Empty tubes, provided as the fourth choice in the test apparatus, were entered much less often than tubes containing live males. Females of all species chose “wrong” males about equally frequently. These observations suggest that even non-conspecific males possess some degree of attractiveness to virgin females. Chemicals in the sex pheromone of the males are presumed to be the source of the males' attractancy. The incomplete species specificity is interpreted in light of the life history of this genus, and it is suggested that specific recognition cues operate primarily after the sexes come together. Supported by a grant from Kagoshima Prefecture in Japan under the exchange program of faculty members between Kagoshima University and the University of Georgia.     

Cross-reactivity between human and canine helper and suppressor T cell antigens using monoclonal antibodies RPA-T4 and HuLy-m8

The murine monoclonal antibodies RPA-T4 and HuLy-m8, specific for a framework determinant of human helper/inducer and suppressor/cytotoxic T cell antigens, cross-reacted with canine cell membrane molecules recognizing a biomolecular complex (50,000 to 55,000 daltons) similar to that described in humans. We investigated the distribution of these helper and suppressor T cell-like antigens on canine peripheral blood lymphocytes. With complement-mediated lymphocytotoxicity, 34% and 35% of the canine lymphocytes expressed the helper T cell-like antigens and the suppressor-like T cell antigens, respectively. When the lymphocytes were treated with RPA-T4 and HuLy-m8, the respective helper and suppressor function was significantly inhibited.     

Application of the tryptophanase promoter to high expression of the tryptophan synthase gene inEscherichia coli

Summary The application of an inducible regulation system using the trytophanase operon promoter (TPase promoter; P_tna) was examined for its high expression of the tryptophan synthase (TS) gene in Escherichia coli. The main problem in the application of P_tna for industrial purposes is catabolite repression by glucose, since glucose is the most abundant carbon source. However, this problem could be avoided by changing glucose to an organic acid, such as succinate, fumarate, malate and acetate, in the course of cultivation after glucose initially added was completely consumed. Under these conditions, l-tryptophan was also used to induce tryptophan synthase. Thus, the specific activity of TS in E. coli strain no. 168 harbouring pBR322F-P_tnaTS was increased 500-fold compared to that of the cultured host strain. About 1 mol l-tryptophan/l reaction mixture was formed from indole and l-serine at 37° C for 3.5 h. Offprint requests to: H. Yukawa     

Electrotransformation of intact cells ofBrevibacterium flavum MJ-233

Summary Electroporation allowed transformation of intact cells ofBrevibacterium flavum MJ-233. The two plasmids used for electroporation were pCRY2 (6.3 kilobases) and pCRY3 (8.2 kilobases). Both plasmids contain the chloramphenicol-resistance gene and the autonomous replication origin inB. flavum MJ-233. The efficiency of electrotransformation was optimal with cells harvested at the middle log phase of growth, and was imporved by the addition of 1.0U/ml of penicillin G to the culture medium. The optimum yield of transformants per g DNA was 5×10⁴ when the cell suspension was pulsed at a cell density of 1×10¹⁰/ml and at a DNA amount of 1.0g.     

Purification and properties of thiamine-binding proteins from sesame seed

Three thiamine-binding proteins of 17-19 kDa (STBP-I, II, and III) were purified from sesame seed (Sesamum indicum L.). Each of the proteins was composed of two subunits of equal molecular mass and each subunit consisted of a large polypeptide and a small polypeptide linked by a disulfide bond(s). They were rich in glutamic acid (or glutamine) and arginine. Their binding activities were optimal at neutral pH. They bound specifically free thiamine but not thiamine phosphates. STBP-I had higher affinity for thiamine than STBP-II or STBP-III. STBP-II and STBP-III bound one molecule of thiamine per molecule, and STBP-I bound 0.5 molecule. The amino acid composition and structure of the STPBs were similar to those of 2S storage proteins.     

Identification of some abnormal metabolites in psoriatic nail using gas chromatography—mass spectrometry

A gas chromatographic—mass spectrometric analysis was used to separate and identify abnormal compounds in the nail of psoriatic patients. The nail was extracted with heated ethanol, and the extract was analyzed with and without trimethylsilylation. Tetradecanoic acid octadecyl ester, hexadecanoic acid octadecyl ester and octadecanoic acid octadecyl ester were first identified in the psoriatic nail, but were not detected in normal nail.     

13C Nuclear magnetic resonance study of salt induced conformational change of basic polypeptides: Poly (L-lysine), poly (L-arginine), and poly (L-ornithine)

A ¹³C-nmr study of the salt-induced helix–coil transition of the basic polypeptides poly(L -lysine) [(Lys)_n], poly(L -arginine) [(Arg)_n], and poly (L -ornithine) [(Orn)_n] was performed to serve as a reference of the helical portion of histones and other proteins. As is the case with pH-induced helix–coil transition, the downfield displacement of the C^α and carbonyl carbon signals are observed in the helical state. The upfield shift of the C^β signals, on the other hand, is noted in the salt-induced transition. Regardless of the differences in the side chains and also the salts used, very similar helix-induced chemical shifts are obtained for (Lys)_n and (Arg)_n. However, the displacement of the C^α, C^β, and carbonyl carbons of (Orn)n in the presence of 4M NaClO₄ is found to be almost 50% of that of (Lys)_n and (Arg)_n. This is explained by the fact that the maximum helical content is about 50%, consistent with the ORD result. Further, the motion of the backbone and side chains of the helical from was estimated by measuring the spin-lattice relaxation time (T₁), nuclear Overhauser enhancement (NOE), and line width. In the case of (Lys)_n, the motion of the side chains is charged very little in comparison with that of the random coil. Indicating that the aggregation of the salt-induced helix is small in contrast to that of the pH-induced helix. For (Arg)_n, however, the precipitate of the helical polymers is mainly due to aggregation.     

Patterns of Genetic Diversity in Rare and Common Orchids Focusing on the Korean Peninsula: Implications for Conservation

To provide basic information for orchid conservation, we surveyed the plant allozyme literature to summarize genetic diversity and structure data for (i) rare orchids native to the Korean Peninsula, and (ii) their congeners irrespective of being common and rare or Korean or not. A total of 68 taxa (32 taxa in Korea and 37 outside Korea; Goodyera repens being included in both datasets) were considered in this study. Overall, rare Korean orchid species had significantly lower levels of genetic diversity than their common congeners and common orchids in general at both population and species levels. However, mean values of G _ST (or F _ST) for rare and common orchids (Korean or not) did not differ significantly from each other. We found patterns of both low and high genetic diversity in rare Korean orchids. Many rare orchids harbored a complete lack of allozyme variation or extremely low within-population variation, perhaps due to rarity associated with random genetic drift and/or, for the case of warm-temperate orchids, to founder effects during post-glacial re-colonization. In contrast, high levels of genetic variation were found for a few orchids that have become recently rare (due to over-collection during the past several decades), probably because there have not been sufficient generations for the initial diversity to be substantially eroded. In addition, several orchids occurring in the main mountain system of the Korean Peninsula (the Baekdudaegan), that served as a glacial refugium, maintained moderate to high levels of within-population genetic diversity. Based on our genetic data, conservation priority should be given to rare orchid species. Particularly, urgent measures should be implemented on Jeju Island, a popular vacation spot, because it also a hotspot for threatened orchids with low levels of genetic diversity.     

Mitochondria-specific RNA-modifying enzymes responsible for the biosynthesis of the wobble base in mitochondrial tRNAs. Implications for the molecular pathogenesis of human mitochondrial diseases

Human mitochondrial (mt) tRNA(Lys) has a taurine-containing modified uridine, 5-taurinomethyl-2-thiouridine (taum5s2U), at its anticodon wobble position. We previously found that the mt tRNA(Lys), carrying the A8344G mutation from cells of patients with myoclonus epilepsy associated with ragged-red fibers (MERRF), lacks the taum5s2U modification. Here we describe the identification and characterization of a tRNA-modifying enzyme MTU1 (mitochondrial tRNA-specific 2-thiouridylase 1) that is responsible for the 2-thiolation of the wobble position in human and yeast mt tRNAs. Disruption of the yeast MTU1 gene eliminated the 2-thio modification of mt tRNAs and impaired mitochondrial protein synthesis, which led to reduced respiratory activity. Furthermore, when MTO1 or MSS1, which are responsible for the C5 substituent of the modified uridine, was disrupted along with MTU1, a much more severe reduction in mitochondrial activity was observed. Thus, the C5 and 2-thio modifications act synergistically in promoting efficient cognate codon decoding. Partial inactivation of MTU1 in HeLa cells by small interference RNA also reduced their oxygen consumption and resulted in mitochondria with defective membrane potentials, which are similar phenotypic features observed in MERRF.     

Mycobiont diversity and first evidence of mixotrophy associated with Psathyrellaceae fungi in the chlorophyllous orchid Cremastra variabilis

Mixotrophy (MX, also called partial mycoheterotrophy) in plants is characterized by isotopic abundances that differ from those of autotrophs. Previous studies have evaluated mycoheterotrophy in MX plants associated with fungi of similar ecological characteristics, but little is known about the differences in the relative abundances of ¹³C and ¹⁵N in an orchid species that associates with several different mycobionts species. Since the chlorophyllous orchid Cremastra variabilis Nakai associates with various fungi with different ecologies, we hypothesized that it may change its relative abundances of ¹³C and ¹⁵N depending on the associated mycobionts. We investigated mycobiont diversity in the chlorophyllous orchid C. variabilis together with the relative abundance of ¹³C and ¹⁵N and morphological underground differentiation (presence or absence of a mycorhizome with fungal colonization). Rhizoctonias (Tulasnellaceae, Ceratobasidiaceae, Sebacinales) were detected as the main mycobionts. High differences in δ¹³C values (– 34.7? to?– 27.4 ‰) among individuals were found, in which the individuals associated with specific Psathyrellaceae showed significantly high relative abundance of ¹³C. In addition, Psathyrellaceae fungi were always detected on individuals with mycorhizomes. In the present study, MX orchid association with non-rhizoctonia saprobic fungi was confirmed, and the influence of mycobionts on morphological development and on relative abundance of ¹³C and ¹⁵N was discovered. Cremastra variabilis may increase opportunities to gain nutrients from diverse partners, in a bet-hedging plasticity that allows colonization of various environmental conditions.