Deletion of the CAP10 gene of Cryptococcus neoformans results in a pleiotropic phenotype with changes in expression of virulence factors

The human pathogen Cryptococcus neoformans causes meningo-encephalitis. The polysaccharide capsule is an important virulence factor for this yeast-like fungus. Previously, we had shown that disruption of the CAP10 gene, encoding a putative xylosyltransferase, results in mutant cells that lack most of the capsular polysaccharides on the cell surface, but do not show a typical acapsular phenotype. In contrast to the acapsular cap59 mutant, cap10 did not induce maturation of dendritic cells when exposed to components of the immune system. In order to gain further insight into the causes of this phenotype displayed by the cap10 mutant, we performed a more in-depth phenotypic analysis of the cell wall and surface structures of this mutant compared to the wild type strain and acapsular mutant cap59. Moreover, we analyzed the cap10 mutant and the wild type strain for differential gene expression of, amongst others, enzymes that are involved in biogenesis of cell wall and capsule components. We conclude that a mutation in the CAP10 gene results in a pleiotropic phenotype with effects on different cellular processes affecting, amongst others, cell size, expression of virulence factors and size of extracellular vesicles.     

Culture of preimplantation embryos and its long-term effects on gene expression and phenotype

A growing number of medical, scientific and biotechnological procedures rely on culture of mammalian preimplantation embryos. This review presents currently available data on aberrant offspring development that sometimes arises from commonly applied in-vitro procedures in humans, ruminant species and mice. Comparison between mammalian species reveals similarities in the phenotypic abnormalities that are observed at fetal and perinatal stages of development. In particular, aberrant effects on fetal growth have been observed in multiple studies in which serum complemented the preimplantation culture medium. Although it remains to be determined whether there is a common causal mechanism(s) involved, several hypotheses have been put forward to account for the variety of the observed developmental abnormalities. One of these postulates that culture can result in the epigenetic deregulation of developmentally important genes, and that such epigenetic alterations would affect in particular the expression of genes that are subject to genomic imprinting. Imprinted genes play key roles in the control of fetal growth, and altered imprinting can cause growth defects. Some recent in-vitro culture studies on mice and ruminant species now lend support to this hypothesis.     

Waardenburg syndrome and Hirschsprung disease: evidence for pleiotropic effects of a single dominant gene

Segregation and linkage analysis was performed on published data on 5 families segregating for Waardenburg syndrome (WS) and Hirschsprung disease (HRSD). Two of these families demonstrated parental consanguinity. On the basis of these families, autosomal recessive inheritance of the combination WS-HRSD has been postulated. However, a single dominant gene with pleiotropic effects leading to WS and HRSD, with a more severe phenotype in homozygotes, is more plausible. A model of gene action incorporating stochastic effects is compatible with these observations.     

Brain development in hydrocephalic-polydactyl,a recessive pleiotropic mutant in the mouse

Summary Animals homozygous for the recessive, pleiotropic, mutation hpy (hydrocephalic-polydactyl) progressively lag behind their wild-type littermates in increase in body weight and brain dry weight over the period from 1–40 days post-partum; many homozygotes die within the first 14 days after birth. Light microscope observations of serial sections of brains revealed a mild to severe dilation of the entire ventricular system and damaged ependyma. Ciliated ependymal cells appeared reduced in number and destruction of ependymal cells over wide areas of the ventricular surfaces was observed. Preliminary scanning electron microscope studies confirmed the light microscope observations and revealed large numbers of erythrocytes and phagocytes associated with the ependymal surface. Neither the histological studies nor experiments involving intracerebral injections of tracer dyes demonstrated obstruction or stenosis of the aqueduct of Sylvius. Individual neurons appeared to be present in normal numbers and to be developing normally and at the same rate as in wild-type animals.Aided by a grant from The National Foundation-March of DimesThe authors wish to express their thanks to Dr. W.F. Hollander who supplied one of us (J.H.D.B.) with original breeding stock, and to Dr. W.J. Humphreys, Director, Central Electron Microscope Laboratory, University of Georgia, for use of the scanning electron microscope facility     

Confidence intervals for candidate gene effects and environmental factors in population-based association studies of families

Complex diseases are influenced by both genetic and environmental factors. Studies of individuals or of families can be used to examine the association of genetic factors, such as candidate genes, and other risk factors with the presence or absence of complex disorders. If families are investigated, whether or not they are randomly ascertained, possible familial correlation among observations must be considered. We have compared two statistical approaches for analyzing correlated binary data from randomly ascertained nuclear families. The generalized estimating equations approach (GEE) can be used to adjust for familial correlation. The relationship between covariates and the response is modelled, and the correlations among family members are treated as nuisance parameters. For comparison, we have proposed two strategies from a hierarchical nonparametric bootstrap approach. One strategy (S1) samples family units, preserving the structure and correlation within each family. A second and novel strategy (S2) also samples family units but then randomly samples offspring with replacement in each family. We applied the methods to data from a study of cardiovascular disease, and followed up with a simulation study in which family data were generated from an underlying multifactorial genetic model. Although the bootstrap approach was more computationally demanding, it outperformed the GEE in terms of confidence interval coverage probabilities for all sample sizes considered.     

围产期和环境因素对早产儿体格发育的影响

对283名4-9岁的早产儿进行体格发有追踪调查，并随机选择283名足月正常体重儿做对照。结果显示：6岁前早产儿身高、体重、头围明显低于足月地统计学存在显著差异（P＜0.05），7岁后身高、体重逐渐接近正常儿,但头团仍低于足月儿（P＜0.01）。影响早产儿体格发育因素作多元逐步回归表明：新生儿住院时间、出生孕周、体重、孕期营养、生后喂养方式、新生儿期症病、家庭经济收入、父母受教育年限为主要危险因素。根据本次研究结果我们提出：（1）提高孕妇保健知识，加强孕期营养，防止早产。（2）在NICU病房实行母婴同室，尽早开始母乳喂养，减少新生儿期疾病，缩短住院时间。（3）出院后对极低体重儿增加体检次数，发现问题及时采取相应措施，使早产儿生长潜力充分发挥出来。     

Low glutathione pools in the original pso3 mutant of Saccharomyces cerevisiae are responsible for its pleiotropic sensitivity phenotype

The original pso3-1 mutant isolate of the yeast Saccharomyces cerevisiae exhibits a pleiotropic mutagen-sensitivity phenotype that includes sensitivity to UVA-activated 3-carbethoxypsoralen, to UVC-light, to mono- and bi-functional nitrogen mustard, to paraquat, and to cadmium; on the other hand, it shows hyper-resistance (HYR) to nitrosoguanidine when compared to established wild-type strains. Also, the original pso3-1 mutant exhibits a low UVC-induced mutability and mitotic gene conversion and a high rate of spontaneous and UVC-induced petite mutations. Since the HYR to the nitrosoguanidine (MNNG) phenotype resembles that of low glutathione-containing yeast cells, the original pso3-1 mutant was crossed to a gsh1 knock-out mutant that lacks the enzyme for the first step in glutathione biosynthesis and the resulting diploid was tested for complementation. While there was none for HYR to nitrosoguanidine, and other low glutathione-related phenotypes, some other phenotypic characteristics of pso3-1, e.g. UVC sensitivity and UVC-induced mutability were restored to a wild-type level. Tetrad analysis of a diploid derived from a cross of the original haploid pso3-1 isolate with a repair-proficient, normal glutathione-containing, PSO3 GSH1 wild-type led to the separation of a leaky gsh1 mutation phenotype from that of the repair-deficient pso3-1 phenotype. Linkage studies by tetrad and random spore analyses indicated no linkage of the two genes. This shows that the low glutathione content in the original pso3-1 isolate is due to a second, additional, mutation in the GSH1 locus and is unrelated to the pso3-1 mutation. Thus, the original pso3-1 isolate is a pso3-1 gsh1 double mutant with most of the particular characteristics of the pleiotropic sensitivity phenotype contributed by either the pso3-1 or the gsh1-leaky mutant allele. The expression of a few phenotypic characteristics of pso3, however, were most pronounced in pso3-1 mutants with a low glutathione pool. Received: 16 August / 24 September 1997     

Genetic and environmental risk factors for the development of food allergy

PURPOSE OF REVIEW: To review recent clinical and experimental studies of genetic and environmental risk factors for the development of food allergy. RECENT FINDINGS: It may be true, although it is yet to be shown, that food allergies in early childhood are becoming more common and that the causes are the same as for later-developing respiratory allergies. The mother not only transfers 50% of her genes to her baby, but she is also the exclusive environment during gestation and continues to be a major environmental factor while breast-feeding her infant. Non-genetic maternal influences increasing the likelihood of food allergy include Caesarian section and high maternal age. Allergy to sesame seems to be increasing in children. This is possibly a consequence of increased use in processed foods. The search for dietary risk factors is not limited to allergenic foods, but may include other nutrients, for example excessive intake of vitamins. Two meta-analyses have seriously questioned the use of special infant formulas for allergy prevention. Novel prevention strategies, such as probiotic bacteria, have yet to be documented further. SUMMARY: The causes of food allergy are still unknown and no particular genes associated particularly with food allergy have been identified, although there is a strong association in general between genetic susceptibility to food allergy and that to IgE-mediated allergy. There are still no measures for general recommendation in order to prevent food allergy and no genes have been linked conclusively to disease. Further research concentrating on food allergy is obviously needed.     

Testing the effects of FSHD candidate gene expression in vertebrate muscle development

The genetic lesion leading to facioscapulohumeral muscular dystrophy (FSHD) is a dominant deletion at the 4q35 locus. The generally accepted disease model involves an epigenetic dysregulation in the region resulting in the upregulation of one or more proximal genes whose overexpression specifically affects skeletal muscle. However, multiple FSHD candidate genes have been proposed without clear consensus. Using Xenopus laevis as a model for vertebrate development our lab has studied the effects of overexpression of the FSHD candidate gene ortholog, frg1 (FSHD region gene 1), showing that increased levels of frg1 systemically led specifically to an abnormal musculature and increased angiogenesis, the two most prominent clinical features of FSHD. Here we studied the overexpression effects of three other promising FSHD candidate genes, DUX4, DUX4c, and PITX1 using the same model system and methods for direct comparison. Expression of even very low levels of either DUX4 or pitx1 early in development led to massive cellular loss and severely abnormal development. These abnormalities were not muscle specific. In contrast, elevated levels of DUX4c resulted in no detectable adverse affects on muscle and DUX4c levels did not alter the expression of myogenic regulators. This data supports a model for DUX4 and PITX1 in FSHD only as pro-apoptotic factors if their expression in FSHD is confined to cells within the myogenic pathway; neither could account for the vascular pathology prevalent in FSHD. Taken together, increased frg1 expression alone leads to a phenotype that most closely resembles the pathophysiology observed in FSHD patients.     

Role of environmental factors on brain development and nerve growth factor expression.

Numerous evidences suggest that early life events can affect the development of the nervous system, contributing in shaping interindividual differences in vulnerability to stress or psychopathology. A number of studies have shown that mothering style in rodents can produce neuroendocrine, neurochemical, and behavioral changes in the adult, although the basic mechanisms initiating this cascade of events still need to be investigated. This paper reviews research performed in our and other laboratories investigating some of the features characterizing hypothalamic--pituitary--adrenal (HPA) axis activity of rodents during early development, with a special emphasis on extrinsic, social regulatory factors, such as the mother and the siblings. In addition, a possible role for neurotrophins as mediators of the effects of external manipulations on brain development is suggested.     

p27: a pleiotropic regulator of cellular phenotype and a target for cell cycle dysregulation in cancer

The eukaryotic cell cycle is regulated by the sequential activation of cyclin-dependent kinases (CDKs). CDK activation is regulated by phosphorylation of the catalytic subunit, by binding to activating (cyclins) and inactivating subunits (cyclin-dependent kinase inhibitor). In this review, we will focus on the role of the cyclin-dependent kinase inhibitor p27 which has been recently the subject of extensive work. This negative regulator of cell growth indeed illustrates the pleiotropic biological effects of such molecules in both normal and cancer cells and the complexity of the regulatory mechanisms involved.     

Importance of environmental factors for the development of liver cirrhosis

The frequency of cirrhoses drastically increased in the seventies. This increase was predominantly due to an augmentation of alcoholic cirrhosis in men. Cirrhosis is significantly more wide-spread in men than in women. Most of the cirrhoses in women are of unknown origin. Morphologically, the alcoholic cirrhoses are of the micronodular types in their great majority. Combined with HBsAg positivity, the macronodular type is most frequent. The classification in micro- and macronodular cirrhoses do not imply a different etiology but it may indicate different stages in cirrhosis of identic origin. Histologically, the signs of alcoholic hepatitis particularly help to trace back the alcoholic etiology. If HBsAg can be detected and the margins of the pseudolobules are moth- eatenlike , this speaks for a hepatitic origin. The lowest average age was observed in cases of alcoholic cirrhoses, the highest in HBsAg positive cirrhoses of women. Men suffering from cirrhosis die earlier than women. In the case of alcoholic origin, the bulk of the cirrhotic livers are eutrophic while, beside HBsAg positivity, the atrophic livers are prevailing. The two most frequent environmental causes of cirrhosis are alcoholic beverages and hepatitis. Better exploration of the environmental factors and clearing up the origin of cryptogenic cirrhoses are essential tasks of the future.     

Growth,development, and gene expression in a persistent Streptococcus gordonii biofilm

A model for the protracted (30-day) colonization of smooth surfaces by Streptococcus gordonii that incorporates the nutrient flux that occurs in the oral cavity was developed. This model was used to characterize the biphasic expansion of the adherent bacterial population, which corresponded with the emergence of higher-order architectures characteristic of biofilms. Biofilm formation by S. gordonii was observed to be influenced by the presence of simple sugars including sucrose, glucose, and fructose. Real-time PCR was used to quantify changes in expression of S. gordonii genes known or thought to be involved in biofilm formation. Morphological changes were accompanied by a significant shift in gene expression patterns. The majority of S. gordonii genes examined were observed to be downregulated in the biofilm phase. Genes found to be upregulated in the biofilm state were observed to encode products related to environmental sensing and signaling.     

Role of IL-10 gene polymorphisms on the susceptibility for esophageal cancer and its association with environmental factors

We conducted a hospital-based case-control study to investigate the association of three common SNPs (-1082G/A rs1800896, -819T/C rs1800871, and -592A/C rs1800872) of IL-10 gene polymorphisms with the susceptibility to esophageal cancer in a Chinese population. 246 patients with pathologically proven esophageal cancer and 492 healthy control subjects were collected in our study. Genotyping of IL-10-1082G/A rs1800896, -819T/C rs1800871, and -592A/C rs1800872 was performed using the Sequenom MassARRAY platform (Sequenom; San Diego, CA). Unconditional logistic regression analyses showed that subjects carrying the AA genotype and GA+AA genotype of IL-10-1082G/A rs1800896 were associated with an increased risk of esophageal cancer, and the adjusted ORs (95% CI) were 2.19 (1.31-3.64) and 1.44 (1.05-1.99), respectively. However, we did not find significant association of IL-10-819T/C rs1800871 and -592A/C rs1800872 with the development of esophageal cancer. By stratification analysis, we found that IL-10-1082G/A rs1800896 polymorphism has no significant association with smoking, drinking and family history of cancer in the first relatives in esophageal cancer risk (P>0.05). In conclusion, IL-10-1082G/A rs1800896 genetic variation may be employed as candidate biomarkers for the prediction of susceptibility in esophageal cancer.     

Immunological reactivity of the host as an environmental factor and its significance for the development of parasitism]

Concepts--mainly of SPRENT (1959, 1963), DINEEN (1963) and DAMIAN (1964)--concerning the immunological aspects of the phylogeny of host-parasite associations and the function of immune processes in the host-parasite relationship are discussed. In the light of some recent findings an integrating interpretation of the available body of evidence is attempted. The significance of the immuno-selection pressure during the course of host-parasite coevolution is stressed and some of the consequences of this pressure seen in the existing host-parasite systems are pointed out.