Fitness of Karyotypes in DROSOPHILA PSEUDOOBSCURA

In the dynamics of the survival of chromosomal polymorphism selection may be operating at the genic level, at the chromosomal level or at the supergene level. Tests designed to distinguish between these levels were run on Drosophila pseudoobscura. There was no evidence for heterosis, a necessary requirement for gene-determined chromosomal polymorphism. A strong chromosmal selection was observed. No evidence was found for the presence within one locality of more than a single superallele for each supergene (= gene order). These results are compared to those found by others.     

Canine erythrocyte pyruvate kinase. II. Properties of the abnormal enzyme associated with hemolytic anemia in the basenji dog

We have compared the solubility, kinetic, immunological, and electrophoretic properties of erythrocyte pyruvate kinase from normal dogs and Basenji dogs with congenital hemolytic anemia due to pyruvate kinase deficiency. Differences can be detected between the two enzymes by all methods. The enzyme from the affected animals has a greater solubility in ammonium sulfate. It has a lower K _m for phosphoenolpyruvate, while the K _m for ADP is increased. This enzyme is not inhibited by ATP or activated by fructose 1,6-diphosphate. The enzyme from the affected animals has none of the allosteric properties characteristic of the normal canine enzyme. No difference can be detected by enzyme inactivation with rabbit antiserum against the human erythrocyte enzyme, but a slight spur is observed on comparison of the two enzymes by Ouchterlony immunodiffusion. The enzymes also differ in their electrophoretic mobilities on starch gel electrophoresis.     

An evaluation of the micronuclei test using triethylenemelamine,trimethylphosphate, hycanthone and niridazole

To determine the feasibility of the micronuclie procedure for cytogenetic studies, a comparatively weak chromosome breaking agent, trimethylphosphate (TMP) and the potent alkylating agent, triethylenemelamine (TEM) were evaluated. The procedure followed was that of Matter and Schmid with the following modifications: (a) direct flushing of bone marrow with 0.2 ml calf fetal serum, (b) air drying slides for a period of only 1 h, and (c) the use of pH 6.0 phosphate buffer to dilute both the Wright and Giemsa stains.With this technique a dose-response curve was generated for both TMP and TEM, using mice as the experimental animal. With TMP, a doubling over background was found when a concentration of 0.5 g/kg per day for five days was administered. To establish a statistically significant doubling dose over the control, a minimum of five animals must be used woth 2000 polychromatic cells being analyzed per animal.Of the two antischistosomal agents tested, hycanthone yielded an increase of 20-fold in the number of mircronuclei over control at 40 mg/kg administered i.p. for five days, while with niridazole no increase in micronuclei at several concentrations tested both by single and multiple injection was found.The results obtained with these compounds compare favorably woth what has been reported for the standard in vivo metaphase analysis.     

Filamentous bacterial viruses. XI. Molecular architecture of the class II (Pf1, Xf) virion

The diffraction patterns of the Pf 1 and Xf strains of filamentous bacterial viruses (class II) can be interpreted in terms of a simple helix of protein subunits with 15Åpitch, having 22 units in five turns. The protein subunits are each elongated in an axial direction, and also slope radially, so as to overlap each other, giving an arrangement of subunits reminiscent of scales on a fish. The protein helix forms a tube with inner diameter about 20Åand outer diameter about 60Å. The single-stranded circular DNA is contained within this tube, with two DNA strands running the length of the tube.The diffraction patterns of fd, If 1 and IKe (class I) can be interpreted in terms of a perturbed version of the class II simple helix.     

Phylogenetic Exploration of Nosocomial Transmission Chains of 2009 Influenza A/H1N1 among Children Admitted at Red Cross War Memorial Children’s Hospital,Cape Town,South Africa in 2011

Traditional modes of investigating influenza nosocomial transmission have entailed a combination of confirmatory molecular diagnostic testing and epidemiological investigation. Common hospital-acquired infections like influenza require a discerning ability to distinguish between viral isolates to accurately identify patient transmission chains. We assessed whether influenza hemagglutinin sequence phylogenies can be used to enrich epidemiological data when investigating the extent of nosocomial transmission over a four-month period within a paediatric Hospital in Cape Town South Africa. Possible transmission chains/channels were initially determined through basic patient admission data combined with Maximum likelihood and time-scaled Bayesian phylogenetic analyses. These analyses suggested that most instances of potential hospital-acquired infections resulted from multiple introductions of Influenza A into the hospital, which included instances where virus hemagglutinin sequences were identical between different patients. Furthermore, a general inability to establish epidemiological transmission linkage of patients/viral isolates implied that identified isolates could have originated from asymptomatic hospital patients, visitors or hospital staff. In contrast, a traditional epidemiological investigation that used no viral phylogenetic analyses, based on patient co-admission into specific wards during a particular time-frame, suggested that multiple hospital acquired infection instances may have stemmed from a limited number of identifiable index viral isolates/patients. This traditional epidemiological analysis by itself could incorrectly suggest linkage between unrelated cases, underestimate the number of unique infections and may overlook the possible diffuse nature of hospital transmission, which was suggested by sequencing data to be caused by multiple unique introductions of influenza A isolates into individual hospital wards. We have demonstrated a functional role for viral sequence data in nosocomial transmission investigation through its ability to enrich traditional, non-molecular observational epidemiological investigation by teasing out possible transmission pathways and working toward more accurately enumerating the number of possible transmission events.     

Commitment to fruiting in synchronously developing cultures of the basidiomycete Schizophyllum commune

Summary 1. A simple technique is described for obtaining large numbers of localized and synchronized fruit bodies of Schizophyllum commune by lowering the carbon dioxide level in mated cultures. 2. The fruiting process is unaffected by a continuous supply of glucose (0.4–2%). However, synchrony and commitment are lost when the glucose concentration is raised to 4%. 3. Five per cent carbon dioxide inhibits the further development of fruit bodies at all stages except the expansion of the already formed basidiocarp. 4. Fruit bodies can develop at 30°C when a CO₂ trapping agent is employed, contrary to previous reports. 5. A possible relationship between the rate of vegetative growth and the initiation of fruiting is discussed.     

Functional activity of RLIM/Rnf12 is regulated by phosphorylation-dependent nucleocytoplasmic shuttling

The X-linked gene Rnf12 encodes the ubiquitin ligase really interesting new gene (RING) finger LIM domain–interacting protein (RLIM)/RING finger protein 12 (Rnf12), which serves as a major sex-specific epigenetic regulator of female mouse nurturing tissues. Early during embryogenesis, RLIM/Rnf12 expressed from the maternal allele is crucial for the development of extraembryonic trophoblast cells. In contrast, in mammary glands of pregnant and lactating adult females RLIM/Rnf12 expressed from the paternal allele functions as a critical survival factor for milk-producing alveolar cells. Although RLIM/Rnf12 is detected mostly in the nucleus, little is known about how and in which cellular compartment(s) RLIM/Rnf12 mediates its biological functions. Here we demonstrate that RLIM/Rnf12 protein shuttles between nucleus and cytoplasm and this is regulated by phosphorylation of serine S214 located within its nuclear localization sequence. We show that shuttling is important for RLIM to exert its biological functions, as alveolar cell survival activity is inhibited in cells expressing shuttling-deficient nuclear or cytoplasmic RLIM/Rnf12. Thus regulated nucleocytoplasmic shuttling of RLIM/Rnf12 coordinates cellular compartments during mammary alveolar cell survival.     

Nutrition and sickle cell disease

A common observation in sickle cell disease is growth retardation, in particular, wasting. Wasting is associated with increased hospitalization and possibly poorer clinical outcomes. Therefore understanding the mechanism of wasting is crucial and reducing the degree of wasting by improving the nutritional status, holds the potential for modifying the course of the disease.     

Optical Magnetic Resonances in Subwavelength Ag–MgF2–Ag Grating Structures

Optical magnetic responses were demonstrated in subwavelength Ag–MgF₂–Ag grating structures for transverse magnetic-polarized light. The subwavelength Ag–MgF₂–Ag grating structures were fabricated using e-beam lithography followed by a lift-off process. By fixing the Ag–MgF₂–Ag strip dimension, the effect of the stripe width on the magnetic resonances was compared for two different grating pitches. With further reduced grating pitch, we pushed the optical magnetic resonances to near UV (deep blue). Numerical simulations confirmed our experimental observations and were in good agreement with the experimental results.