Cytoplasmic recycling of 60S preribosomal factors depends on the AAA protein Drg1

Allelic forms of DRG1/AFG2 confer resistance to the drug diazaborine, an inhibitor of ribosome biogenesis in Saccharomyces cerevisiae. Our results show that the AAA-ATPase Drg1 is essential for 60S maturation and associates with 60S precursor particles in the cytoplasm. Functional inactivation of Drg1 leads to an increased cytoplasmic localization of shuttling pre-60S maturation factors like Rlp24, Arx1, and Tif6. Surprisingly, Nog1, a nuclear pre-60S factor, was also relocalized to the cytoplasm under these conditions, suggesting that it is a previously unsuspected shuttling preribosomal factor that is exported with the precursor particles and very rapidly reimported. Proteins that became cytoplasmic under drg1 mutant conditions were blocked on pre-60S particles at a step that precedes the association of Rei1, a later-acting preribosomal factor. A similar cytoplasmic accumulation of Nog1 and Rlp24 in pre-60S-bound form could be seen after overexpression of a dominant-negative Drg1 variant mutated in the D2 ATPase domain. We conclude that the ATPase activity of Drg1 is required for the release of shuttling proteins from the pre-60S particles shortly after their nuclear export. This early cytoplasmic release reaction defines a novel step in eukaryotic ribosome maturation.     

High Compliance with Newborn Community-to-Facility Referral in Eastern Uganda:.An Opportunity to Improve Newborn Survival

Background

Seventy-five percent of newborn deaths happen in the first-week of life, with the highest risk of death in the first 24-hours after birth.WHO and UNICEF recommend home-visits for babies in the first-week of life to assess for danger-signs and counsel caretakers for immediate referral of sick newborns. We assessed timely compliance with newborn referrals made by community-health workers (CHWs), and its determinants in Iganga and Mayuge Districts in rural eastern Uganda.

Methods

A historical cohort study design was used to retrospectively follow up newborns referred to health facilities between September 2009 and August 2011. Timely compliance was defined as caretakers of newborns complying with CHWs’ referral advice within 24-hours.

Results

A total of 724 newborns were referred by CHWs of whom 700 were successfully traced. Of the 700 newborns, 373 (53%) were referred for immunization and postnatal-care, and 327 (47%) because of a danger-sign. Overall, 439 (63%) complied, and of the 327 sick newborns, 243 (74%) caretakers complied with the referrals. Predictors of referral compliance were; the newborn being sick at the time of referral- Adjusted Odds Ratio (AOR) = 2.3, and 95% Confidence-Interval (CI) of [1.6 - 3.5]), the CHW making a reminder visit to the referred newborn shortly after referral (AOR =1.7; 95% CI: [1.2 -2.7]); and age of mother (25-29) and (30-34) years, (AOR =0.4; 95% CI: [0.2 - 0.8]) and (AOR = 0.4; 95% CI: [0.2 - 0.8]) respectively.

Conclusion

Caretakers’ newborn referral compliance was high in this setting. The newborn being sick, being born to a younger mother and a reminder visit by the CHW to a referred newborn were predictors of newborn referral compliance. Integration of CHWs into maternal and newborn care programs has the potential to increase care seeking for newborns, which may contribute to reduction of newborn mortality.     

Babesia microti: Biochemistry and function of hamster erythrocytes infected from a human source

Babesia microti, a protozoan parasite of mammalian erythrocytes was obtained from the blood of an infected human and maintained in golden hamsters, in which a parasitemia of 70% was obtained regularly. The hamsters' response—a subacute, hemolytic anemia—was studied with regard to oxygen affinity and red cell organic phosphate content. In addition, the reduced glutathione status of infected erythrocytes was observed because of the possible importance of this metabolite to parasite growth and red cell integrity. Infected animals developed a severe anemia with reticulocytosis; there occurred a 4-mm decrease in whole blood oxygen affinity without any change in erythrocytes' 2,3-diphosphoglycerate levels. The glutathione content of the infected animals' erythrocytes increased twofold during the course of the infection. In uninfected animals, in which anemia and reticulocytosis had been produced by bleeding, all changes seen in infected animals were reproduced. It was concluded that the changes in the infected animals were due to the anemia and reticulocytosis alone, and that the parasite played no role in these changes apart from being a cause of anemia and reticulocytosis.     

Metabolism of Acetate to Amino Acids in Brains of Rats After Complete Hepatectomy

Abstract: The concentration of glutamine increases in the brain after hepatectomy. In the present studies the conversion of intravenously given [¹⁴C]acetate to [¹⁴C]glutamate and [¹⁴C]glutamine was studied in control rats and in rats at 6 h after complete hepatectomy. The incorporation of label into glutamate was only slightly inhibited, but the further incorporation into glutamine was greatly inhibited, after hepatectomy. These data, and previous data using [¹⁴C]glucose as precursor, indicate that synthesis of glutamine in brain is inhibited after hepatectomy, and suggest that its concentration must increase because degradation is inhibited to an even greater extent.     

SPECTRAL SENSITIVITY IN TWO SPECIES OF PINNIPEDS (PHOCA VITULINA AND OTARIA FLAVESCENS)

Spectral sensitivity was measured in air in the light adapted state in two harbor seals and a South American sea lion using a behavioral training technique. Increment thresholds were determined in a spectral range from 390 nm to 670 nm in a simultaneous two‐choice discrimination task. The spectral sensitivity curves show two maxima in sensitivity, one main peak with a maximum around 500 nm in the harbor seal and around 550 nm in the South American sea lion, and a second, smaller peak with a maximum in the range of 410 nm in both species. The broad shape and the position of the maximum of the spectral sensitivity curve of the harbor seals suggests that even under photopic conditions both rods and cones are contributing to the measurements since harbor seals possess only one cone type. The maximum sensitivity in the green part of the spectrum may indicate an adaptation to a specific underwater environment.     

The Economic Burden of Meningitis to Households in Kassena-Nankana District of Northern Ghana

Objective

To estimate the direct and indirect costs of meningitis to households in the Kassena-Nankana District of Ghana.

Methods

A Cost of illness (COI) survey was conducted between 2010 and 2011. The COI was computed from a retrospective review of 80 meningitis cases answers to questions about direct medical costs, direct non-medical costs incurred and productivity losses due to recent meningitis incident.

Results

The average direct and indirect costs of treating meningitis in the district was GH¢152.55 (US$101.7) per household. This is equivalent to about two months minimum wage earned by Ghanaians in unskilled paid jobs in 2009. Households lost 29 days of work per meningitis case and thus those in minimum wage paid jobs lost a monthly minimum wage of GH¢76.85 (US$51.23) due to the illness. Patients who were insured spent an average of GH¢38.5 (US$25.67) in direct medical costs whiles the uninsured patients spent as much as GH¢177.9 (US$118.6) per case. Patients with sequelae incurred additional costs of GH¢22.63 (US$15.08) per case. The least poor were more exposed to meningitis than the poorest.

Conclusion

Meningitis is a debilitating but preventable disease that affects people living in the Sahel and in poorer conditions. The cost of meningitis treatment may further lead to impoverishment for these households. Widespread mass vaccination will save households'' an equivalent of GH¢175.18 (US$117) and impairment due to meningitis.     

Genotyping of Mycoplasma bovis isolates using multiple-locus variable-number tandem-repeat analysis

Mycoplasma bovis has been considered an important cause of mastitis, pneumonia, and arthritis in bovines with a highly detrimental economic impact in the livestock industry. Previous epidemiological studies, using different typing techniques showed that the isolates were usually heterogeneous and results were difficult to compare between different laboratories. Reliable and comparable molecular typing techniques using geographically and temporal distinct isolates have never been used. The objective of this study was to use multiple-locus variable-number tandem-repeat analysis (MLVA) for the differentiation of M. bovis isolates. This typing scheme was developed using the sequenced genome of the M. bovis PG45 type strain. Nine tandem-repeat sequences were selected and the genetic diversity of 37 isolates of wide geographic and temporal origins was analyzed. The results were compared to those obtained with random amplified polymorphic DNA (RAPD) analysis and pulsed-field gel electrophoresis (PFGE) for the same isolates. Cluster concordance between techniques was evaluated using Adjusted Rand and Wallace coefficients, and different cutoff levels of similarity were tested. Acceptable values of ≥0.5 for all techniques for the Wallace coefficient were only observed at the most relaxed cutoff level, i.e., 52% for MLVA, 29% for PFGE and 18% for RAPD. The Simpson's index of diversity was 0.91 for MLVA, 0.99 for RAPD analysis and 0.99 for PFGE. This MLVA assay is compatible with simple PCR and agarose gel-based electrophoresis steps as well as with high-throughput automated methods. The molecular typing scheme presented in this study provides a fast, reliable, and cost-effective typing method for surveillance of M. bovis epidemiology.     

Restraint of proinflammatory cytokine biosynthesis by mitogen-activated protein kinase phosphatase-1 in lipopolysaccharide-stimulated macrophages

Exposure of macrophages to LPS elicits the production of proinflammatory cytokines, such as TNF-alpha, through complex signaling mechanisms. Mitogen-activated protein (MAP) kinases play a critical role in this process. In the present study, we have addressed the role of MAP kinase phosphatase-1 (MKP-1) in regulating proinflammatory cytokine production using RAW264.7 macrophages. Analysis of MAP kinase activity revealed a transient activation of c-Jun N-terminal kinase (JNK) and p38 after LPS stimulation. Interestingly, MKP-1 was induced concurrently with the inactivation of JNK and p38, whereas blocking MKP-1 induction by triptolide prevented this inactivation. Ectopic expression of MKP-1 accelerated JNK and p38 inactivation and substantially inhibited the production of TNF-alpha and IL-6. Induction of MKP-1 by LPS was found to be extracellular signal-regulated kinase dependent and involved enhanced gene expression and increased protein stability. Finally, MKP-1 expression was also induced by glucocorticoids as well as cholera toxin B subunit, an agent capable of preventing autoimmune diseases in animal models. These findings highlight MKP-1 as a critical negative regulator of the macrophage inflammatory response, underscoring its premise as a potential target for developing novel anti-inflammatory drugs.     

Oogenesis in the terrestrial hermit crab Coenobita clypeatus (decapoda,anomura). I. Previtellogenic oocytes

Ultrastructural study of previtellogenic oocytes found in cystlike clusters scattered throughout the length of the bilobed ovary of the hermit crab Coenobita clypeatus shows a high nuclear:cytoplasm ratio. Large, round nuclei containing synaptinemal complexes serve as good temporal markers for identification of previtellogenic oocytes. The cytoplasm contains many smooth-membraned vesicles filled with granules and probably of nuclear origin. In addition to its complement of Golgi complexes, endoplasmic reticulum, mitochondria, and free ribosomes, the cytoplasm also contains stacks of annulate lamellae, a feature not previously described for decapod oocytes. Typically, the previtellogenic oocyte with its accumulation of ribosomes has the appearance of a nonsynthetic cell preparing to go through a metabolic transition.