Reassessment of presumed Y/22 and Y/15 translocations in man using a new technique.

A new chromosome banding technique, distamycin A plus DAPI, has been used to reexamine cases of presumed Y/autosome translocations. In contrast with the results obtained with quinacrine fluorescence (Q-banding), the satellites of acrocentric chromosomes do not fluoresce brightly with this new (DA-DAPI) method, making it more specific for the long arm of the Y chromosome. Previous cases with intensely Q-fluorescent and abnormally long short arms on a chromosome 22 were considered as presumptive 22/Y translocations: The new technique clearly shows that, in these cases, the additional material on 22p is not derived from Yq. In contrast, in other cases the Yq nature of additional material on 15p, in conjunction with the presence of an extra Y-body in interphase nuclei and the presence of a male-specific DNA, supports the previous diagnosis of a presumptive 15/Y translocation.     

Preimplantation Genetic Diagnosis and Natural Conception: A Comparison of Live Birth Rates in Patients with Recurrent Pregnancy Loss Associated with Translocation

Background

Established causes of recurrent pregnancy loss (RPL) include antiphospholipid syndrome, uterine anomalies, parental chromosomal abnormalities, particularly translocations, and abnormal embryonic karyotypes. The number of centers performing preimplantation genetic diagnosis (PGD) for patients with translocations has steadily increased worldwide. The live birth rate with PGD was reported to be 27-54%. The live birth rate with natural conception was reported to be 37-63% on the first trial and 65-83% cumulatively. To date, however, there has been no cohort study comparing age and the number of previous miscarriages in matched patients undergoing or not undergoing PGD. Thus, we compared the live birth rate of patients with RPL associated with a translocation undergoing PGD with that of patients who chose natural conception.

Methods and Findings

After genetic counseling, 52 patients who desired natural conception and 37 patients who chose PGD were matched for age and number of previous miscarriages and these comprised the subjects of our study. PGD was performed by means of fluorescence in situ hybridization analysis. The live birth rates on the first PGD trial and the first natural pregnancy after ascertainment of the carrier status were 37.8% and 53.8%, respectively (odds ratio 0.52, 95% confidence interval 0.22-1.23). Cumulative live birth rates were 67.6% and 65.4%, respectively, in the groups undergoing and not undergoing PGD. The time required to become pregnancy was similar in both groups. PGD was found to reduce the miscarriage rate significantly. The prevalence of twin pregnancies was significantly higher in the PGD group. The cost of PGD was $7,956 U.S. per patient.

Conclusions

While PGD significantly prevented further miscarriages, there was no difference in the live birth rate. Couples should be fully informed of the similarity in the live birth rate, the similarity in time to become pregnancy, the advantages of PGD, such as the reduction in the miscarriage rate, as well as its disadvantages, such as the higher cost, and the advantages of a natural pregnancy, such as the avoidance of IVF failure. The findings presented here should be incorporated into the genetic counseling of patients with RPL and carrying a translocation.     

Medical Genetic Study of the Rostov Oblast Population: Changes in Reproductive Parameters with Time

Changes in vital statistics and Crow's indices during the past 50 years have been studied on the basis of answers to 2165 questionnaires divided into five groups according to the age of women surveyed.     

Structural Organization of the Human Genome: Distribution of Nucleotides,AluRepeats, and Exons in Chromosomes 21 and 22

Analysis of DNA sequences of the human chromosomes 21 and 22 performed using a specially designed MegaGene software allowed us to obtain the following results. Purine and pyrimidine nucleotide residues are unevenly distributed along both chromosomes, displaying maxima and minima (waves) with a period of about 3 Mbp. Distribution of G+C along both chromosomes has no distinct maxima and minima, however, chromosome 21 contains considerably less G+C than chromosome 22. Both exons and Alurepeats are unevenly distributed along chromosome 21: they are scarce in its left part and abundant in the right part, while MIR elements are quite monotonously spread along this chromosome. The Alurepeats show a wave-like distribution pattern similar for both repeat orientations. The number of the Alurepeats of opposite orientations was equal for both studied chromosomes, and this may be considered a new property of the human genome. The positive correlation between the exon and Aludistribution patterns along the chromosome, the concurrent distribution of Alurepeats in both orientations along the chromosome, and the equal copy numbers for Aluin direct and inverted orientations within an individual chromosome point to their important role in the human genome, and do not fit the notion that Alurepeats belong to parasitic (junk) DNA.     

Results of Laboratory Testing of 15 Cookstove Designs in Accordance with the ISO/IWA Tiers of Performance

EcoHealth - The widespread adoption and sustained use of modern cookstoves has the potential to reduce harmful effects to climate, health, and the well-being of approximately one-third of the...     

Rab17 and Rab18, Small GTPases with Specificity for Polarized Epithelial Cells: Genetic Mapping in the Mouse

The Rab subfamily of small GTPases plays an important role in the regulation of membrane traffic in eukaryotic cells. While most Rab proteins are equally expressed in polarized and nonpolarized cells, Rab17 and Rab18 show epithelial cell specificity. Here we report the genetic mapping of Rab17 and Rab18 on mouse chromosomes 1 and 18, respectively. We also discuss some implications ofRab17andRab18mapping, including their candidacy for the mouse mutationsln(leaden),Tw(twirler), andax(ataxia).     

Variation of Reproductive Traits and Female Body Size in the Most Widely-Ranging Terrestrial Reptile: Testing the Effects of Reproductive Mode, Lineage, and Climate

The European common lizard, Zootoca vivipara, is the most widespread terrestrial reptile in the world. It occupies almost the entire Northern Eurasia and includes four viviparous and two oviparous lineages. We analysed how female snout-vent length (SVL), clutch size (CS), hatchling mass (HM), and relative clutch mass (RCM) is associated with the reproductive mode and climate throughout the species range and across the evolutionary lineages within Z. vivipara. The studied variables were scored for 1,280 females and over 3,000 hatchlings from 44 geographically distinct study samples. Across the species range, SVL of reproductive females tends to decrease in less continental climates, whereas CS corrected for female SVL and RCM tend to decrease in climates with cool summer. Both relationships are likely to indicate direct phenotypic responses to climate. For viviparous lineages, the pattern of co-variation between female SVL, CS and HM among populations is similar to that between individual females within populations. Consistent with the hypothesis that female reproductive output is constrained by her body volume, the oviparous clade with shortest retention of eggs in utero showed highest HM, the oviparous clade with longer egg retention showed lower HM, and clades with the longest egg retention (viviparous forms) had lowest HM. Viviparous populations exhibited distinctly lower HM than the other European lacertids of similar female SVL, many of them also displaying unusually high RCM. This pattern is consistent with Winkler and Wallin’s model predicting a negative evolutionary link between the total reproductive investment and allocation to individual offspring.     

Functional Genetic Variants of TNFSF15 and Their Association with Gastric Adenocarcinoma: A Case-Control Study

The purpose of this study was to identify functional genetic variants in the promoter of tumor necrosis factor superfamily member 15 (TNFSF15) and evaluate their effects on the risk of developing gastric adenocarcinoma. Forty DNA samples from healthy volunteers were sequenced to identify single nucleotide polymorphisms (SNPs) in the TNFSF15 promoter. Two TNFSF15 SNPs (−358T>C and −638A>G) were identified by direct sequencing. Next, genotypes and haplotypes of 470 gastric adenocarcinoma patients and 470 cancer-free controls were analyzed. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by logistic regression. Serologic tests for Helicobacter pylori infection were measured by enzyme-linked immuno-sorbent assay (ELISA). Subjects carrying the TNFSF15 −358CC genotype were at an elevated risk for developing gastric adenocarcinoma, compared with those with the −358TT genotype (OR 1.42, 95% CI, 1.10 to 2.03). H. pylori infection was a risk factor for developing gastric adenocarcinoma (OR 2.31, 95% CI, 1.76 to 3.04). In the H. pylori infected group, subjects with TNFSF15 −358CC genotype were at higher risks for gastric adenocarcinoma compared with those carrying −358TT genotype (OR: 2.01, 95%CI: 1.65 to 4.25), indicating that H. pylori infection further influenced gastric adenocarcinoma susceptibility. The −358 T>C polymorphism eliminates a nuclear factor Y (NF-Y) binding site and the −358C containing haplotypes showed significantly decreased luciferase expression compared with −358T containing haplotypes. Collectively these findings indicate that functional genetic variants in TNFSF15 may play a role in increasing susceptibility to gastric adenocarcinoma.     

Regulation of Phytochrome Message Abundance in Root Caps of Maize : Spatial, Environmental, and Genetic Specificity

In many cultivars of maize (Zea mays L.) red light affects root development via the photomorphogenetic pigment phytochrome. The site of perception for the light is the root cap. In the maize cultivar Merit, we investigated phytochrome-mediated events in the cap. We established that the message encoded by the phyA1 gene was most abundant in dark-grown tissue and was asymmetrically distributed in the root cap, with greatest expression in the cells which make up the central columella core of the cap. Phytochrome message was negatively autoregulated in a specific region within the root cap. This autoregulation was sensitive to very-low-fluence red light, and thus was characterized as a phytochrome-mediated, very-low-fluence event. The kinetics of message reaccumulation in the dark were also examined and compared to the kinetics of the light requirement for root gravitropism in this cultivar. Similarly, the degree of autoregulation present in two other maize cultivars with different light requirements for gravitropic sensitivity was investigated. It appears that the Merit cultivar expresses a condition of hypersensitivity to phytochromemediated light regulation in root tissues. We conclude that phytochrome regulates many activities within the cap, but the degree to which these activities share common phytochrome-mediated steps in not known.     

Chromosomes of caryophyllidean cestodes: Diploidy, triploidy, and parthenogenesis in Glaridacris catostomi

Mitotic and meiotic chromosomes were studied in Giemsa post-stained Feulgen squashes of testicular, ovarian, and vitelline cells. G. catostomi is 2n = 20 with eight pairs of metacentrics and two pairs of submetacentrics in its karyotype. The fundamental number of chromosome arms is FN = 40. At mitotic metaphase the mean total chromosome length (TCL) of the complement was 111·4 μm; the largest chromosomes were 8 μm (7% TCL) and the smallest 3 μm (3% TCL). Karyotype variation was not found among five diploid populations from New York State and Canada. Meiotic activity was abundant in spermatogenesis which proceeds as usual with sperm developing after two meiotic divisions. Chiasma frequency at diakinesis was 37/cell; as many as five chiasmata were observed in a single bivalent. A triploid ‘race’ (3n = 30) of G. catostomi was discovered in Bozenkill Creek near Albany, New York. Karyotype analysis confirms the triploid nature of these variants. Spermatogenesis in triploids is abnormal to the point of complete failure. The presence of an extra set of chromosomes has resulted in a breakdown of meiosis with subsequent sterility of the male system. Eggs remain unfertilized and parthenogenetic reproduction is presumed to occur. The possible origins of this unusual condition and its evolutionary implications are discussed. Seventeen figures, two tables of measurements, and a system of chromosome nomenclature supplement the paper.     

Genetic analysis and complementation by germ-line transformation of lethal mutations in the unc-22 IV region of Caenorhabditis elegans

Summary The subject of this study is the organization of essential genes in the 2 map-unit unc-22 IV region of the Caenorhabditis elegans genome. With the goal of achieving mutational saturation of essential genes in this region, 6491 chromosomes mutagenized with ethyl methanesulfonate (EMS) were screened for the presence of lethal mutations in the unc-22 region. The genetic analysis of 21 lethal mutations in the unc-22 region resulted in the identification of 6 new essential genes, making a total of 36 characterized to date. A minimum of 49 essential genes are estimated to lie in this region. A set of seven formaldehyde-induced deficiencies of unc-22 and surrounding loci were isolated to facilitate the positioning of essential genes on the genetic and physical maps. In order to study essential genes at the molecular level, our approach was to rescue lethal mutations by the injection of genomic DNA in the form of cosmid clones into the germ-line of balanced heterozygotes carrying a lethal mutation. The cosmid clones containing let-56 and let-653 were identified by this method.     

Global Potential Energy Minima of SPC/E Water Clusters without and with Induced Polarization Using a Genetic Algorithm

The global minimum potential energy structures of water clusters, (H₂O) _n , n = 2-14, have been calculated for the SPC/E (Simple Point Charge/Extended) model and a recent fluctuating charge version of the latter using a simple genetic algorithm. The SPC/E cluster geometries are in good agreement with previous TIP3P (Transferable Intermolecular Potential-3 Point) and TIP4P (Transferable Intermolecular Potential-4 Point) calculations as well as the interpretation of experimental measurements. In contrast to this, the polarizable version of the SPC/E model, which is based on the fluctuating charge approach, deviates rather strongly for n=6 with few exceptions. However, comparing the polarizable model to ab initio results for identical cluster geometries we find reasonable agreement for the magnitude of the average molecular dipole moment, the corresponding energy per molecule, and the average oxygen-oxygen distance as functions of n.Electronic Supplementary Material available.     

Preferential fluorescent staining of heterochromatic regions in human chromosomes 9, 15, and the Y by D 287/170

Summary The utility of a newly synthesized chemical variation of DAPI (4-6-diamidino-2-phenyl-indole), D 287/170, for differential staining of constitutive heterochromatin in man is demonstrated. Direct staining of human chromosomes with D 287/170 results in brilliant fluorescence of the paracentromeric C-band of chromosome 9, of a proximal short-arm segment of chromosome 15 and of certain heterochromatic regions in the Y. Bright, but less conspicuous fluorescence is occassionally seen at the centromeres of other chromosomes. The staining differentiation obtained by D 287/170 is very distinct, and the intensity of the fluorescent light is unusually high. The new fluorochrome should prove particularly useful for detecting and analyzing human chromosome 9 heterochromatin at various stages of the cell cycle in normal and structurally altered chromosomes.