Evolution of Human Polyomavirus JC: Implications for the Population History of Humans

The polyomavirus JC virus (JCV), the etiological agent of progressive multifocal leukoencephalopathy, is ubiquitous in the human population, infecting children asymptomatically, then persisting in the kidney. The main mode of transmission of JCV is from parents to children through long-term cohabitation. Twelve JCV subtypes that occupy unique domains in Europe, Africa, and Asia have been identified. Here, we attempted to elucidate the evolutionary relationships among JCV strains worldwide using the whole-genome approach with which a highly reliable phylogeny of JCV strains can be reconstructed. Sixty-five complete JCV DNA sequences, derived from various geographical regions and belonging to 11 of the 12 known subtypes, were subjected to phylogenetic analysis using three independent methods: the neighbor-joining, maximum parsimony, and maximum likelihood methods. The trees obtained with these methods consistently indicated that ancestral JCVs were divided into three superclusters, designated as Types A, B, and C. A split in Type A generated two subtypes, EU-a and -b, mainly containing European and Mediterranean strains. The first split in Type B generated Af2 (the major African subtype). Subsequent splits in Type B generated B1-c (a minor European subtype) and all seven Asian subtypes (B1-a, -b, -d, B2, MY, CY, and SC). Type C generated a single subtype (Af1), consisting of strains derived from western Africa. While the present findings provided a basis on which to classify JCV into types or subtypes, they have several implications for the divergence and migration of human populations. Received: 4 April 2001 / Accepted: 31 July 2001     

Behavioral and hormonal responses of men to brief interactions with women

This study tested for behavioral and hormonal reactions of young men to brief social encounters with potential mating partners. Male college students were randomly assigned to engage in a short conversation with either a young man (male condition) or a young woman (female condition). Participants provided saliva samples before and after the conversation, completed a battery of psychological measures after the interaction, and had their behavior rated by their conversation partners. Salivary testosterone (T) increased significantly over baseline levels in the female condition only, though differences between conditions were not significant. In addition, change in T was significantly correlated with the degree to which the female confederates thought the male participants were trying to impress them. These behavioral ratings, in turn, were correlated with the participants' ratings of the female confederates as potential romantic partners. Results were generally consistent with the hypothesis that human males may exhibit a behavioral and endocrine courtship response that is similar to that observed in males of many nonhuman vertebrate species.     

Direct anabolic metabolism of three-carbon propionate to a six-carbon metabolite occurs in vivo across tissues and species

Anabolic metabolism of carbon in mammals is mediated via the one- and two-carbon carriers S-adenosyl methionine and acetyl-coenzyme A. In contrast, anabolic metabolism of three-carbon units via propionate has not been shown to extensively occur. Mammals are primarily thought to oxidize the three-carbon short chain fatty acid propionate by shunting propionyl-CoA to succinyl-CoA for entry into the TCA cycle. Here, we found that this may not be absolute as, in mammals, one nonoxidative fate of propionyl-CoA is to condense to two three-carbon units into a six-carbon trans-2-methyl-2-pentenoyl-CoA (2M2PE-CoA). We confirmed this reaction pathway using purified protein extracts provided limited substrates and verified the product via LC-MS using a synthetic standard. In whole-body in vivo stable isotope tracing following infusion of ¹³C-labeled valine at steady state, 2M2PE-CoA was found to form via propionyl-CoA in multiple murine tissues, including heart, kidney, and to a lesser degree, in brown adipose tissue, liver, and tibialis anterior muscle. Using ex vivo isotope tracing, we found that 2M2PE-CoA also formed in human myocardial tissue incubated with propionate to a limited extent. While the complete enzymology of this pathway remains to be elucidated, these results confirm the in vivo existence of at least one anabolic three- to six-carbon reaction conserved in humans and mice that utilizes propionate.     

Coordinated expression of matrix Gla protein is required during endochondral ossification for chondrocyte survival

Matrix Gla protein (MGP) is a 14-kD extracellular matrix protein of the mineral-binding Gla protein family. Studies of MGP-deficient mice suggest that MGP is an inhibitor of extracellular matrix calcification in arteries and the epiphyseal growth plate. In the mammalian growth plate, MGP is expressed by proliferative and late hypertrophic chondrocytes, but not by the intervening chondrocytes. To investigate the functional significance of this biphasic expression pattern, we used the ATDC5 mouse chondrogenic cell line. We found that after induction of the cell line with insulin, the differentiating chondrocytes express MGP in a stage-specific biphasic manner as in vivo. Treatment of the ATDC5 cultures with MGP antiserum during the proliferative phase leads to their apoptosis before maturation, whereas treatment during the hypertrophic phase has no effect on chondrocyte viability or mineralization. After stable transfection of ATDC5 cells with inducible sense or antisense MGP cDNA constructs, we found that overexpression of MGP in maturing chondrocytes and underexpression of MGP in proliferative and hypertrophic chondrocytes induced apoptosis. However, overexpression of MGP during the hypertrophic phase has no effect on chondrocyte viability, but it does reduce mineralization. This work suggests that coordinated levels of MGP are required for chondrocyte differentiation and matrix mineralization.     

Effects of type of fat in the diet on iron bioavailability assessed in suckling and weanling rats

Differences in iron bioavailability from human milk and milk formulas may in part be due to differences in lipid composition. We investigated the short and long term effects of diets based on different fats [corn, coconut, olive, or soy oil, human milk fat (HMF) and a formula fat blend (FF)] on iron absorption in rats. Suckling rat pups dosed with 59Fe-labeled diets containing different fat sources were killed after 6 h, and blood and individual tissues were counted. Iron availability was estimated by % 59Fe in blood. Pups dosed with a more saturated fat (coconut oil) had a higher % 59Fe in blood than those fed other fat sources. Weanling rats were used to determine iron bioavailability from fat sources using both the hemoglobin repletion method and whole body counting. Hemoglobin regeneration was significantly higher for rats fed the HMF diet (8.4 +/- 0.5 g/dl) than from the FF diet (6.5+/-0.6 g/dl) or the corn oil diet (less saturated) (6.4 +/- 0.3 g/dl). Rats fed diets based on coconut oil (more saturated) had significantly higher % 59Fe retention (61.6 +/- 1.4) than rats fed diets based on FF (49.8 +/- 3.4). There was a significant positive association between oleic acid in the diet and oleic acid in the intestinal mucosa (r = 0.95, p < 0.05) and between linoleic acid in the diet and linoleic acid in the intestinal mucosa (r = 0.97, p < 0.05) suggesting that the dietary treatment altered the fatty acid composition of the brush border membrane. Our results suggest that saturated fats may increase iron absorption and that part of this may be achieved by changes in the fatty acid composition of the intestinal mucosa. Hemoglobin regeneration and % 59Fe retention data suggest that differences in iron absorption from infant diets may in part be due to differences in fat composition. Therefore, lipid composition of infant formulas should also be taken into consideration as a factor influencing iron bioavailability.     

Subculture of rabbit articular chondrocytes within a collagen gel: growth and analysis of differentiation

Primary cultures of rabbit articular chondrocytes have been subcultured within three-dimensional (3D) collagen gels. Under these conditions, the cells remained viable and divided, but with a lower proliferation rate than that observed in control monolayer cultures. Flow cytometric analysis of progression of the cells into the cell cycle has confirmed and extended these findings. Also the cellular volume was decreased in 3D-culture, being in the same range as thein vivo size of cartilage cells. Specific staining for proteoglycans and type II collagen immunolocalization on sections of gels showed the expression of differentiated phenotypes and revealed the accumulation of these matrix components in the immediate surroundings of the cells. The use of Ultroser G (a serum substitute) improved the conditions for 3D- culture of rabbit articular chondrocytes.     

HPV16l1基因的克隆及其在真核细胞中的表达

克隆并表达人乳头瘤病毒16型(HPV16)晚期基因l1,以期为研制防治宫颈癌的DNA疫苗奠定基础。本实验采用PCR方法从质粒p16L1BN1中获得HPV16l1基因片段,利用基因重组技术,将其克隆至含巨细胞病毒(CMV)启动子的真核表达载体中,核酸序列鉴定HPV16l1基因真核表达质粒构建成功,再用脂质体介导基因转染7721人肝癌细胞。转化阳性细胞经SDS-PAGE显示在分子量大约为55kDa的位置出现一条特异性条带,与HPV16L1分子量大小相符。表达产物经Western blotting分析:能与HPV16L1单克隆抗体特异结合。真核表达质粒pcDNA3-HPV16L1构建成功并能在真核细胞7721中有效表达,为下一步进行动物DNA免疫实验奠定了基础。     

Prehistoric land use as recorded in a lake-shore core at Lake Constance

The second part of a pollen profile from Hornstaad/Lake Constance (Germany), containing the Atlantic and Subboreal (6400 cal B.C. to 700 cal B.C.) is presented. The diagram has a sampling interval of 1 cm and an average time resolution of 10 years. The cereal curve provided the basis for cereal zones, which are used to classify the human impact. Twenty-six cereal zones can be distinguished, most of them divided into subzones, from 5500 cal B.C. to 700 cal B.C. They correspond to both known and, mostly, unknown settlements in the surrounding landscape from the Early Neolithic to the Late Bronze Age. Charcoal and chemical analyses as well as sediment accumulation, confirmed by accelerator dates, provide evidence for human impact on the environment.A contribution to the 8th IPC, Aix-en-Provence, Sept. 1992     

Replication and discrimination of limb movement velocity

It is well known that proprioception is composed of the senses of movement and position. Whereas tests of position sense are quite commonly used, tests of the acuity in perception of movement velocity are scarce. In the present study we examined some novel tests for assessing the sense of limb movement velocity, involving replication and discrimination of single-joint movement velocity. Specifically, we investigated: (1) whether replication of limb movement velocity is more accurate following active criterion movements as compared to passive; (2) whether antagonist muscle contraction during passive limb movement enhances velocity discrimination; (3) how criterion movement velocity influences response accuracy; (4) the relationship between movement velocity and movement extent during velocity replication; and (5) whether subjects really base discrimination of velocities on perceived velocity. Sixteen healthy subjects participated in four tests (I-IV). For each test, horizontal abductions were performed about the right glenohumeral joint from the sagittal plane. The subjects were required to actively replicate the velocity of either an active (Test I) or passive (Test II) criterion movement, or judge whether a passive/semipassive (passive during antagonist muscle contraction) movement was faster or slower than a previous passive/semipassive criterion movement (Test III/IV). The results revealed higher response accuracy for Test I compared to Test II and for slower movements compared to faster, but no difference in response accuracy between Test III and IV. For velocity discrimination, the analysis revealed that the subjects based their judgment on the difference between criterion and comparison velocity rather than time or extent cues.     

Extracellular matrix influences hormone and protein production by human chorionic villi

Summary Increasing evidence confirms that the extracellular matrix greatly influences cell behaviour and function. Collagen and fibrin are in contact with trophoblast throughout pregnancy. To investigate whether these two matrices influence hormon production by the trophoblast, explants from first-trimester chorionic villi were cultured for up to 30 days either a) in medium with agitation, b) embedded in type-I collagen (three-dimensional gels), or c) embedded in fibrin (three-dimensional gels). The supernatant culture medium was changed every 48 h and tested by radioimmunoassay for hCG, progesterone and pregnancy-associated plasma protein A. In addition, after 3, 7, 15, and 30 days of culture villi were fixed and studied by light and electron microscopy. Embedding in the extracellular matrix showed higher and longer-lasting production rates of all measured products and superior structural preservation as compared to cultures with agitation. Collagen matrix proved to be superior to fibrin. As established by several tests, this difference was neither due to thrombin used to polymerize fibrinogen, nor to differences in the diffusion rates through the two different matrices used. We conclude that extracellular matrix, particularly collagen, influences the synthesis of trophoblastic products. Embedding of the villous explants in three-dimensional gels constitutes a new method for long-term cultures of chorionic villi.This study was presented at the workshop Placental-and decidual-specific protein synthesis and secretion: regulation, role and interaction, Zemun, Belgrade, Yugoslavia, 19–20 May, 1988 (Bischof and Castellucci 1988; see also J. Aplin 1989), and at the 11th Rochester Trophoblast Conference, Rochester, N.Y. USA, 9–12 October 1988 (Castellucci et al. 1988)