Rh proteins vs Amt proteins: an organismal and phylogenetic perspective on CO2 and NH3 gas channels.

Rh (Rhesus) proteins are homologues of ammonium transport (Amt) proteins. Physiological and structural evidence shows that Amt proteins are gas channels for NH(3), but the substrate of Rh proteins, be it CO2 as shown in green alga, or NH3/NH4+ as shown in mammalian cells, remains disputed. We assembled a large dataset generated of Rh and Amt to explore how Rh originated from and evolved independently of Amt relatives. Analysis of this rich data implies that Rh was split from Amt first to emerge in archaeal species. The Rh ancestor underwent divergence and duplication along speciation, leading to neofunctionalization and subfunctionalization of the Rh family. The characteristic organismal distribution of Rh vs. Amt reflects their early separation and subsequent independent evolution: they coexist in microbes and invertebrates but do not in fungi, vascular plants or vertebrates. Rh gene-duplication was prominent in vertebrates: while epithelial RhBG/RhCG displayed strong purifying selection, erythroid Rh30 and RhAG experienced different episodes of positive selection in each of which adaptive evolution occurred at certain time points and in a few codon sites. Mammalian Rh30 and RhAG were subject to particularly strong positive selection in some codon sites in the lineage from rodents to human. The grounds of this adaptive evolution may be driven by the necessity to increase the surface/volume ratio of biconcave erythrocytes for facilitative gas diffusion. Altogether, these results are consistent with Rh proteins not being the orthologue of Amt proteins but having gained the function for CO2/HCO3- transport, with important roles in systemic pH regulation.     

大鼠内毒素休克肝线粒体Ca^2＋,Mg^2＋含量变化与线粒体损伤

本文在大鼠内毒素休克模型上，观察了肝线粒体结构和功能与Ｃａ＾２＋，Ｍｇ＾２＋含量变化的关系。结果发现：休克动物肝组织和线粒体的Ｃａ＾２＋浓度升高，Ｍｇ＾２＋浓度下降与正常对照组相比有非常显著性差异；用图像分析仪定量分析显示线粒体结构明显受损，线粒体标志酶之一－琥珀酸脱氢酶（ＳＤＨ）活性明显下降，本文认为组织和线粒体内Ｍｇ＾２＋／Ｃａ＾２＋比值下降是休克细胞不可逆损伤重要因素之一。     

恶性疟原虫抗原基因在鼠伤寒沙门氏菌中的表达及免疫原性的初步鉴定

将人工合成的恶性疟原虫杂合７４肽抗原基因克隆到表达载体ｐＷＲ４５０－１中，获得了重组质粒ｐＷＲＣ，将其先转化到减毒伤寒沙门氏菌ＬＢ５０００修饰后，再转化到ＳＬ３２６１，得到重组减毒鼠伤寒沙门氏菌ＳＬ３２６１（ｐＷＲＣ）。ｐＷＲＣ在ＳＬ３２６１中以β－半乳糖苷酶－杂合多肽抗原Ｃ融合蛋白（ＧＺ－Ｃ）形式表达，表达量约占菌体蛋白总量的１１．３％．Ｗｅｓｔｅｒｎｂｌｏｔ及免疫双扩散显示ＧＺ－Ｃ可与兔抗ＧＺ－Ｃ抗原的免疫血清发生特异反应。ＧＺ－Ｃ识别兔抗ＧＺ－Ｃ及鼠抗恶性疟原虫抗血清的ＥＬＩＳＡ滴度分别为１：３２００及１：５１２０。初步结果表明ＳＬ３２６１（ｐＷＲＣ）表达的ＧＺ－Ｃ具有抗原性。连续传代ＳＬ３２６１（ｐＷＲＣ）未见质粒ｐＷＲＣ丢失及对宿主有明显的毒性。     

Reconstruction of 4-MV bremsstrahlung spectra from measured transmission data

Transmission data for 4-MV bremsstrahlung beams have been measured with a combination of lead and aluminum attenuators. From these data, the original energy spectra have been reconstructed using an iterative least-squares technique, previously evaluated by simulation studies. The spectra on the central axis for three similar 4-MV linear accelerators indicated no significant differences. When studying the spectra at 5 degrees and 9 degrees off the central axis, that at 9 degrees showed the expected increase of low-energy photons. All these spectra showed a maximum photon energy of 4.5 +/- 0.2 MeV. When the magnetron power was reduced, the spectrum on the central axis shifted to lower energies and the maximum photon energy decreased to 3.5 +/- 0.2 MeV. The result of this experimental study confirms the conclusions from the previous stimulation, that the numerical technique for analysis of transmission data can accurately represent 4-MV bremsstrahlung spectra and detect differences in energy distribution with changes in machine tuning and position in the radiation field for a 4-MV bremsstrahlung beam.     

A new haplogroup pattern displayed in Fujian Han in China

Human Y-chromosomal binary polymorphisms have been considered to preserve the paternal genetic legacy and provide evidence on human evolution and the genetic relationships among and demographic history of different populations. To reveal the genetic origin and immigration of the Fujian Han, 13 binary markers on the Y chromosome were used to screen Fujian Han by allele-specific polymerase chain reaction. The results indicated that the M₉G marker was highly prevalent (96.20%), suggesting a significant genetic drift. In addition, M₁₂₂C frequency was only 22.78%, and M₄₅A and M₁₀₃T were default. The distinctive haplogroup frequencies (H₁, H₅, and H_6/7/8) imply that the haplogroup pattern is a relatively ancestral and interim type. Received: October 13, 2001 / Accepted: December 3, 2001     

Covalent crosslinking of myosin subfragment-1 and heavy meromyosin to actin at various molar ratios: Different correlations between ATPase activity and crosslinking extent

Summary This paper describes a systematic study of crosslinking of skeletal muscle myosin subfragment-1 (S1) and heavy meromyosin (HMM) to F-actin in the rigor state with 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide (EDC). We followed the time courses of S1 or HMM head crosslinking at various actin:S1 or actin:HMM head molar ratios and the resulting superactivation of ATPase activity. The ATPase activity of the covalent complexes was measured at 0.5 M KCl, where the covalent complexes retain superactivated ATPase activity but the activity of uncrosslinked myosin heads is not activated by actin. S1 crosslinking was slowest at the actin:S1 molar ratio of 11, but faster at larger molar ratios, where more than 80% of added S1 could be crosslinked to actin. In spite of the dependence of crosslinking rate on actinS1 ratio, there were two linear correlations between ATPase activity and the extent of S1 crosslinking to actin: one for S1 crosslinked to actin at actinS1 molar ratios more than 2.71 and the other for S1 crosslinked at a molar ratio of 11. Extrapolation of the former correlation line to 100% crosslinked S1 gave an ATPase activity of 39 s^–1 for actin-S1 covalent complex at 25 °C, whereas that of the other correlation line gave 21 s^–1. The latter smaller activity suggests that the interface between actin and S1 in their rigor complexes at a molar ratio of 11 is different from that at molar ratios of more than 2.71. The acto-HMM crosslinking rate depended on the ratio of actin to HMM head, like that of S1 crosslinking to actin. The ATPase activity of crosslinked actin-HMM was, unlike that of actin-S1 covalent complexes, bell-shaped as a function of the crosslinked heads, but chymotryptic conversion of HMM to S1 in the covalent complexes made the bell-shaped characteristics disappear and increased the activity close to that of actin-Sl covalent complexes. These results indicate that some physical constraint imposed on myosin heads suppresses the actin-activated ATPase activity of HMM crosslinked to actin.     

大鼠催乳素瘤形成过程中催乳素基因的表达

给ＳＤ大鼠皮下埋植内含１７β－雌二醇硅橡胶管３０、６０、１２０天后，发现大鼠垂体重量随给药时间延长呈持续性增加；用放射免疫法测定血浆催乳素含量，亦依次明显升高；用Ｎｏｒｔｈｅｒｎ印迹杂交方法检测垂体细胞中ＰＲＬ基因，发现ＰＲＬ ｍＲＮＡ含量也依次显著增加，但其增加却远低于血浆ＰＲＬ含量的增加，提示β－雌二醇除了促进ＰＲＬ基因的转录外，还可能增加ＰＲＬ ｍＲＮＡ的翻译效率。     

Changing seroepidemiology of hepatitis B, C, and D virus infections in high-risk populations

Needle-sharing and sexual contact are important transmission routes of hepatitis B, C, and D virus (HBV, HCV, HDV) infection. This study aimed to investigate the current status of these viral infections among high-risk populations including prostitutes and intravenous (i.v.) drug users, compared with the prevalence rate reported previously to examine the changing seroepidemiology. Of the 916 female prostitutes, 79 (9%) were positive for antibody to HCV (anti-HCV), 111 (12%) were positive for HBV surface antigen (HBsAg), and 5 (5%) had antibody to HDV (anti-HDV). The prevalence rate was significantly lower compared to that in 1989-1991 (12%, P = 0.037) for HCV infection, and to that in 1988 (59%) and 1996 (40%) (P < 0.0001) for HDV infection. Of the 494 i.v. drug users, 87 (18%) patients were HBsAg carriers and 12 (14%) were anti-HDV-positive. The prevalence rate of HDV infection was significantly lower than that reported in 1985 (79%, P < 0.0001). Among the 443 tested i.v. drug users, 182 (41%) were anti-HCV-positive, significantly lower than that in 1985 (53%, P = 0.026). Of the 263 male prostitutes, 11 (4%) were anti-HCV-positive, 45 (17%) were HBsAg-positive, and 7 (16%) were anti-HDV-positive. Of the 129 illegal immigrant prostitutes, 7 (5%) were anti-HCV-positive, 15 (12%) were HBsAg-positive and none were positive for anti-HDV. In conclusion, the findings indicate a declining prevalence of HCV and HDV infections among drug users and prostitutes over the past 16 years. Male prostitutes and immigrant prostitutes are new "high-risk" populations and may become a reservoir for disease transmission.     

beta2-adrenergic receptor gene polymorphisms in myasthenia gravis (MG)

The beta2-adrenergic receptor (beta2-AR) belongs to the group of G-protein coupled receptors and is present mainly on skeletal and cardiac muscle cells and lymphocytes. The gene encoding beta2-AR (ADRB2) displays a moderate degree of heterogeneity in the human population. The distribution of polymorphisms at amino acid positions 16, 27 and 164 is changed in asthma, hypertension and obesity. We have earlier reported a decreased density of the beta2-AR on peripheral blood mononuclear cells and the presence of beta2-AR antibodies in patients with MG. Since certain polymorphisms affect the function of the beta2-AR, it was of interest to analyse these in MG. Using allele-specific polymerase chain reaction amplification, we revealed an over-representation of homozygosity for Arg16 and a lower prevalence of homozygosity for Gly16 in MG patients compared with healthy individuals. The increased frequency of homozygosity for Arg16 was due to a contribution from patients with generalized MG but not from patients with only ocular disease. Homozygosity for Glu27 was negatively associated with both the presence of beta2-AR antibodies and severity of disease. Moreover, acetylcholine receptor (AChR) antibodies were more often present in patients being homozygous for Gln27. Our results imply that homozygosity for Arg16 confers susceptibility to generalized MG, and that certain polymorphisms at amino acid position 27 are associated with subgroups of patients.