Snapshots of DsbA in action: detection of proteins in the process of oxidative folding

DsbA, a thioredoxin superfamily member, introduces disulfide bonds into newly translocated proteins. This process is thought to occur via formation of mixed disulfide complexes between DsbA and its substrates. However, these complexes are difficult to detect, probably because of their short-lived nature. Here we show that it is possible to detect such covalent intermediates in vivo by a mutation in DsbA that alters cis proline-151. Further, this mutant allowed us to identify substrates of DsbA. Alteration of the cis proline, highly conserved among thioredoxin superfamily members, may be useful for the detection of substrates and intermediate complexes in other systems.     

Epidemiological investigation of the prevalence and features of postweaning multisystemic wasting syndrome in Japan.

To investigate the prevalence and features of postweaning multisystemic wasting syndrome (PMWS) in Japan, an epidemiological study was conducted in 692 weaned pigs with various clinical signs, commonly including wasting or weight loss, collected from 129 swine farms between 2000 and 2003. The presence of PMWS was diagnosed by the detection of characteristic histological lesions and moderate to large amounts of porcine circovirus type 2 (PCV2) antigen within the lesions in multiple lymphoid tissues. Postweaning multisystemic wasting syndrome was positive in 23.4% of pigs (162/692) over the course of the study, and occurred in 50.4% of the farms (65/129). Mortality in 30-120-day-old pigs in the farms positive for PMWS varied from 0.1 to 32.0%. No significant difference in mortality was seen between PMWS-positive and -negative farms (P = 0.1). However, mortality was significantly higher in the PMWS-positive farms where PMWS was diagnosed in more than 50% of the pigs examined compared to farms negative for PMWS (P = 0.02). These findings indicate that PMWS has spread widely in Japan. Moreover it may exist in variable forms in swine farms, including an epidemic form or a subtle endemic or sporadic form. A case-control study suggested that risk factors for the occurrence of PMWS include porcine reproductive and respiratory syndrome (PRRS) pneumonias and Mycoplasma hyorhinis infection.     

Effects of milrinone on hemodynamics and regional blood flow in the hypoxic dog

Milrinone, a therapeutic agent for acute congestive heart failure, has both inotropic and vasodilatory effects, but investigations of these effects of milrinone were almost all conducted under normoxia, and few reports have investigated how milrinone affects the hemodynamics and redistribution of regional blood flow under severe hypoxia. By using colored microspheres, we investigated how milrinone affects hemodynamics and the redistribution of regional blood flow under severe hypoxia. Twelve healthy mongrel dogs were divided into 2 groups. The milrinone group was infused with milrinone cumulatively at 25, 75 and 250 microg/kg for 5 min each. The intact group was infused with saline instead of milrinone. We measured the hemodynamics and cerebrum, cerebellum and kidney blood flow in both groups. Both groups were inspired with 10% oxygen. Milrinone induced significant decrease in mean pulmonary artery and pulmonary vascular resistance, compared with the intact group. In both groups slight decreases in mean arterial pressure, systemic vascular resistance and double-product were seen. In regional blood flow, milrinone-induced increases in blood flow were seen in the cerebrum, cerebellum, and especially in the kidneys. Milrinone's vasodilatory effects were sufficient even under hypoxia. And milrinone increased regional blood flow slightly in the cerebrum and cerebellum, and significantly in the kidneys. These results suggested that milrinone protects against hypoxia-induced organ damage especially in the kidneys. In addition, milrinone is very potent in improving severe congested hemodynamics which complicates hypoxic pulmonary vasoconstriction.     

Phytotoxin produced by the netted scab pathogen, <Emphasis Type="Italic">Streptomyces turgidiscabies</Emphasis> strain 65, isolated in Sweden

Streptomyces spp. are a highly diverse group of bacteria most of which are soil-inhabiting saprophytes. A few are plant pathogens that produce a family of phytotoxins called thaxtomins and cause significant economic losses, e.g., by reducing the marketability of potato tubers (Solanum tuberosum). In northern Europe, S. scabies, S. turgidiscabies and S. europaeiscabiei are the most common plant pathogenic species. In this study, a Streptomyces strain isolated from a netted scab lesion on a tuber of potato cv. Bintje in northern Sweden was identified as S. turgidiscabies but was found to differ in the genomic region carrying genes required for thaxtomin biosynthesis. Our results showed that the strain did not produce thaxtomin but rather phytotoxin fridamycin E, which is an anthraquinone novel to plant pathogenic Streptomyces spp. Fridamycin E was shown to reduce or inhibit sprouting of potato microtubers in vitro. While fridamycin E is known to have antibiotic activity against Gram-positive bacteria, the inhibitory activity of fridamycin E on plant growth is a novel finding.     

Trends of Air Pollution and Its Present Situation in Hiroshima Prefecture

The ambient concentration of SO₂, NOx and O_x in the atmosphere of Hiroshima, Fukuyama and Fuchu city which were monitored by the prefectural monitoring stations, are examined to give a picture of the typical air pollution at these sites. Results show that the yearly concentrations of SO₂ in these areas are significantly fall from 20 to 6 ppb during 1978–1996 when the NOx concentrations having no such significant change which varies from 40 to 30 ppb. The Photo-chemical Oxidant (Ox) increases annually at the rate of 0.3 ppb to 0.6 ppb in Hiroshima city only. To know the present situation of air pollution the Differential Optical Absorption Spectroscopy (DOAS) system is used in the city of Higashi Hiroshima. The daily average concentrations of SO₂, NO₂, O₃ and HONO measured during the period of August 1999 to March 2000 ranged from 1.4 ppb to 2.8 ppb, 13 ppb to 26.9 ppb, 21 ppb to 53.6 ppb and 1 ppb to 4.3 ppb respectively. The patterns of concentrations of NO₂ and O₃ measured by DOAS look similar to the seasonal patterns of NOx and Ox by the conventional system.     

Rubisco small subunits of C4 plants,Napier grass and guinea grass confer C4-like catalytic properties on Rubisco in rice

ABSTRACT

Overexpression of Rubisco small subunit (RbcS) of C₄ plant, sorghum (sorghum bicolor) was shown to enhance the catalytic turnover rate (k _cat) of Rubisco in rice (Oryza sativa). In this study, the effects of other Rubisco small subunits of C₄ plants, Napier grass (Pennisetum purpureum) and guinea grass (Megathyrsus maximus) on kinetic properties of Rubisco in rice were studied. The expression levels of Napier grass RbcS (NgRbcS) and guinea grass RbcS (GgRbcS) proteins accounted for 41% and 45% of total RbcS, respectively in homozygous overexpression lines. The k _cat and K _m for CO₂ (Kc) of Rubisco were increased in all transgenic lines. Interestingly, the k _cat was markedly higher in NgRbcS homozygous line, whereas K _c was notably higher in GgRbcS homozygous line. Although its effects depend on species, these results suggest that the introduction of C₄ RbcS are effective approaches to alter the catalytic properties of Rubisco in rice.     

Acceleration of follicular development by administration of vascular endothelial growth factor in cycling female rats

To address the role of follicular angiogenesis in the determination of ovulatory follicles and the effects of different vascular endothelial growth factor (VEGF) isoforms on follicular angiogenesis and development, mature female rats were treated with an angiogenic inhibitor (TNP-470), and also with VEGF 120 or 164 at different dosages (0.4, 0.8, 4.0 or 8.0 microg/kg body weight) for 3 days during the estrous cycle. Ovarian follicular angiogenesis, the population of large follicles and ovulation were examined. VEGF 120 (0.8 microg/kg) and 164 (8.0 microg/kg) treatments stimulated follicular angiogenesis in the theca interna layer, while TNP-470 treatment showed severe depression of follicular angiogenesis, and completely inhibited ovulation. After administration of VEGF 120 or 164, the number of healthy preovulatory follicles and ovulated oocytes increased significantly, concomitantly with a decrease in the number of atretic preovulatory follicles. The oocytes ovulated had normal fertilizability and developed to term with the same litter size as in the control rats. Our findings suggest that follicular angiogenesis may be a determinant of follicular development during the periovulatory phase, and that VEGF isoforms may play different important roles in regulating follicular angiogenesis.     

Association of BoLA-DRB3 alleles identified by a sequence-based typing method with mastitis pathogens in Japanese Holstein cows

The association of the polymorphism of bovine leukocyte antigen ( BoLA-DRB3 ) genes identified by the polymerase chain reaction sequence-based typing (PCR-SBT) method with resistance and susceptibility to mastitis caused by pathogenic bacteria was investigated. Blood samples for DNA extraction were collected from 194 Holstein cows (41 healthy cows and 153 mastitis cows including 24 mixed-infection cows infected with 2 or 3 species of pathogens) from 5 districts of Chiba prefecture, Japan. Sixteen BoLA-DRB3 alleles were detected. The 4 main alleles of DRB3*0101 , *1501 , *1201 , and *1101 constituted 56.8% of the total number of alleles detected. Mastitis cows were divided into 2 groups: group 1 with single-infection cows and group 2 with all mastitis cows including 24 mixed-infection cows. The differences in the frequencies of BoLA-DRB3 alleles and the number of cows homozygous or heterozygous for each BoLA-DRB3 allele between healthy cows and the 2 groups of mastitis cows were evaluated. Furthermore, similar comparisons were performed between healthy cows and the 2 groups of mastitis cows for each mastitis pathogen. It was considered that the 4 alleles, namely, DRB3*0101 , *1501 , *1201 , and *1101 had specific resistance and susceptibility to 4 different mastitis pathogens. Thus, DRB3*0101 might be associated with susceptibility to coagulase-negative Staphylococci and Escherichia coli , and DRB3*1501 might be associated with susceptibility to Escherichia coli . However, DRB3*1101 might be associated with resistance to Streptococci and coagulase-negative Staphylococci , and DRB3*1201 , with resistance to Streptococci , Escherichia coli , and Staphylococcus aureus .