Centromere pattern in different mouse seminiferous tubule cells

Centromere arrangement in different mouse seminiferous tubule cells was analyzed using an anticentromere antiserum from a patient with the CREST syndrome of scleroderma. A peptide of 18 kd was recognized by this serum on immunoblotting of mouse nuclear proteins from seminiferous tubule cells. In the cells studied by immunofluorescence, different patterns of centromere arrangement were observed. A speckled arrangement of centromeres was found in spermatogonia, double spots corresponding to meiotic bivalents were found in pachytene cells, and clusters of a haploid numer of centromeres were found in early and acrosome phase spermatids. In Sertoli cells, only three centromeric spots were detected, corresponding to the nucleolar organizer chromosome pairs. A relationship between the functional stage of the cell and the arrangement of and conformational changes in the centromeres is considered.     

Phosphorylation of alpha-tubulin carboxyl-terminal tyrosine prevents its incorporation into microtubules

Insulin receptor kinase phosphorylated tubulin in an insulin-dependent fashion. Two different populations of phosphotubulin were found. In tubulin dimers containing tyrosine at the carboxyl-terminal of their alpha subunit, phosphate was incorporated in that residue, and the phosphorylated protein did not assemble into polymers. In tubulin dimers lacking this tyrosine residue, phosphate was incorporated into different tyrosine residues located in other parts of the molecule, and the phosphoprotein retained its capacity to polymerize.     

Oogenesis in the Apogamous Fern Pteris cretica

The events that characterize egg formation and maturation inPteris cretica were investigated using transmission electronmicroscopy and electron microscope microprobe analysis. Theydid not differ significantly from those described for sexuallyreproducing ferns. The significance of these findings is discussedin relation to current theories concerning phase change in ferns. Pteris cretica, fern, apogamy, agamospory, transmission electron microscopy, oogenesis     

Breast and Bottle Feeding as Risk Factors for Dental Caries: A Systematic Review and Meta-Analysis

Understanding the role that breastfeeding and bottle feeding play in the development of dental caries during childhood is essential in helping dentists and parents and care providers prevent the disease, and also for the development of effective public health policies. However, the issue is not yet fully understood. The aim of this systematic review and meta-analysis was to search for scientific evidence in response to the question: Do bottle fed children have more dental caries in primary dentition than breastfed children? Seven electronic databases and grey literature were used in the search. The protocol number of the study is PROSPERO CRD 42014006534. Two independent reviewers selected the studies, extracted data and evaluated risk of bias by quality assessment. A random effect model was used for meta-analysis, and the summary effect measure were calculated by odds ratio (OR) and 95% CI. Seven studies were included: five cross-sectional, one case-control and one cohort study. A meta-analysis of cross-sectional studies showed that breastfed children were less affected by dental caries than bottle fed children (OR: 0.43; 95%CI: 0.23–0.80). Four studies showed that bottle fed children had more dental caries (p<0.05), while three studies found no such association (p>0.05). The scientific evidence therefore indicated that breastfeeding can protect against dental caries in early childhood. The benefits of breastfeeding until age two is recommended by WHO/UNICEF guidelines. Further prospective observational cohort studies are needed to strengthen the evidence.     

On the Photosynthetic Potential in the Very Early Archean Oceans

In this work we apply a mathematical model of photosynthesis to quantify the potential for photosynthetic life in the very Early Archean oceans. We assume the presence of oceanic blockers of ultraviolet radiation, specifically ferrous ions. For this scenario, our results suggest a potential for photosynthetic life greater than or similar to that in later eras/eons, such as the Late Archean and the current Phanerozoic eon.     

Association of casein kinase II with microtubules

A magnesium-dependent heparin-inhibited protein kinase activity associated with brain microtubule preparations has been identified as casein kinase II using a monospecific polyclonal antibody. This enzyme appears enriched in cold-stable microtubule fractions. By immunofluorescence microscopy using an antiserum against casein kinase II, the in situ immunolabeling of some microtubule assays has been observed. Thus, mitotic spindles are stained by the anti-casein kinase II antibody in fibroblast cells. In neuroblastoma cells induced to differentiate, the labeling of microtubule arrays inside developing axon-like processes is also seen. These results support the view that casein kinase II can modulate cytoskeletal assembly and dynamics through phosphorylation of microtubule proteins.     

A new tritoniid species (Mollusca: Opisthobranchia) from Bouvet Island

Tritoniid sea slugs (Mollusca, Gastropoda, Opisthobranchia) are reported for the first time from Bouvet Island. Tritonia dantarti sp. n. shows morphological and anatomical differences with regard to the two previously known tritoniids reported from Antarctica and Sub-Antarctica, Tritonia vorax (Odhner 1926) and Tritonia challengeriana Bergh, 1884. Regarding the external morphology, T. dantarti sp. n. is characterized by a very bright orange coloration in the dorsum, white dorsal crests, highly ramified dendritic gills (the largest vertically orientated and the rest laterally orientated), and a quadrangular cross section. The radula presents very long, thin lateral teeth and the jaws present mainly unicuspidate, striated denticles. The seminal receptacle is large, pear-shaped and its grey pigmentation differs from the rest of the genital system. The Antarctic species T. challengeriana was also found in waters off Bouvet Island, while the Subantarctic species T. vorax was not found.