Participation of alkaline phosphatase in the active transport of phosphates in brush border membrane vesicles

This paper reports the separation and preliminary characterization of the products formed by the reaction of the antitumor compound cis-Pt(NH₃)₂Cl₂ with DNA. Electrophoresis of the acid hydrolysed platinum-DNA complex gave a profile of platinum concentration which contained 5 peaks whose relative intensities varied with the amount of cis-Pt(NH₃)₂Cl₂ fixed on the DNA. Similar analysis of the products formed between DNA and trans-Pt(NH₃)₂Cl₂ or [Pt(dien)Cl]Cl, which are not active antitumor agents, indicated that these compounds bound to DNA in a different manner than cis-Pt(NH₃)₂Cl₂. DNA isolated from Escherichia coli which had been treated with cis-Pt(NH₃)₂Cl₂ or [Pt(dien)Cl]Cl did not give the same electrophoresis profiles as the corresponding platinum-DNA complexes formed in vitro.     

Loss of Panx1 Impairs Mammary Gland Development at Lactation: Implications for Breast Tumorigenesis

Pannexin1 (Panx1) subunits oligomerize to form large-pore channels between the intracellular and extracellular milieu that have been shown to regulate proliferation, differentiation and cell death mechanisms. These key cellular responses are ultimately necessary for normal tissue development and function but the role of Panx1 in development, differentiation and function in many tissues remains unexplored, including that of the breast. Panx1 was identified to be expressed in the mammary gland through western blot and immunofluorescent analysis and is dynamically upregulated during pregnancy and lactation. In order to evaluate the role of Panx1 in the context of mammary gland development and function, Panx1^-/- mice were evaluated in comparison to wild-type mice in the mammary glands of virgin, lactating and involuting mice. Our results revealed that Panx1 ablation did not affect virgin or involuting mammary glands following histological and whole mount analysis. Panx1 was necessary for timely alveolar development during early lactation based on a decreased number of alveolar lumen following histological analysis and reduced proliferation following Ki67 immunofluorescent labelling. Importantly, the loss of Panx1 in lactating mammary glands did not overtly affect epithelial or secretory differentiation of the mammary gland suggesting that Panx1 is not critical in normal mammary gland function. In addition, PANX1 mRNA expression was correlated with negative clinical outcomes in patients with breast cancer using in silico arrays. Together, our results suggest that Panx1 is necessary for timely alveolar development following the transition from pregnancy to lactation, which may have implications extending to patients with breast cancer.     

Effect of phospholipid removal on the kinetics of the metarhodopsin I to metarhodopsin II reaction.

The kinetics of the metarhodopsin (meta) I → metarhodopsin II reaction have been studied by flash photolysis in two different types of preparations of bovine rhodopsin: (i) digitonin-solubilized rod outer segment (ROS) membranes with a molar ratio of phospholipid to rhodopsin of approximately 90, and (ii) digitonin-solubilized phospholipid-free rhodopsin with a molar ratio of phospholipid to rhodopsin of less than 0.2. At 20 °C the kinetics in both preparations are multiexponential, but four terms are required to fit the data with the solubilized membranes, whereas only two are required with the phospholipid-free preparation. Thus, phospholipid removal simplifies the kinetics of the meta I → meta II reaction, but the resulting preparation still does not show first-order kinetics. The ratio of the time constants of these two components with detergent-solubilized phospholipid-free rhodopsin was nearly equal to the values found with ROS particles, rhodopsin-phospholipid recombinants and intact rabbit eyes. This suggests a common origin for these two components in all these preparations and appears to exclude heterogeneity in bound phospholipid as the basis of these two-component kinetics.     

Maternal lineages in native Canadian equine populations and their relationship to the Nordic and Mountain and Moorland pony breeds

A 378-bp section of the mitochondrial displacement loop was used to estimate genetic diversity in the native Canadian equine populations. The inclusion of 10 Mountain and Moorland, 3 Nordic pony breeds, 2 feral populations, and 5 horse breeds were also investigated as they may have influenced the development (or rejuvenation) of the native Canadian populations. A total of 281 samples were sequenced, which produced 75 haplotypes derived from 54 informative sites. On further investigation, 36 of these 75 haplotypes were found to be previously unreported. Overall, total diversity was lowest in the feral Sable Island population with a haplotype diversity (0.27 ± 0.12), nucleotide diversity (0.0007 ± 0.0004), and pairwise difference of 0.286 ± 0.317. This is not surprising due to the geographic isolation of this population. Haplotype diversity was highest (1.00 ± 0.13) in the New Forest population, pairwise difference was highest (8.061 ± 4.028) in the Icelandic breed, whereas nucleotide diversity was highest in the Exmoor breed (0.0209 ± 0.0025). Within the Canadian populations, haplotype diversity was highest in the Newfoundland pony (0.96 ± 0.08), whereas pairwise difference and nucleotide diversity was highest in the Canadian horse (7.090 ± 3.581 and 0.0188 ± 0.0042, respectively). Three different estimates of genetic distances were used to examine the phylogenetic relationships amongst these populations. All 3 estimates produced similar topologies. In general, the native Canadian populations were highly represented in the D clade, with particular emphasis in the D1 and D2 clades. This is an important factor when considering the phylogenetic conservation of these Canadian equine populations.     

Children's development of self-regulation in speech production

Species-specific vocalizations fall into two broad categories: those that emerge during maturation, independent of experience, and those that depend on early life interactions with conspecifics. Human language and the communication systems of a small number of other species, including songbirds, fall into this latter class of vocal learning. Self-monitoring has been assumed to play an important role in the vocal learning of speech and studies demonstrate that perception of your own voice is crucial for both the development and lifelong maintenance of vocalizations in humans and songbirds. Experimental modifications of auditory feedback can also change vocalizations in both humans and songbirds. However, with the exception of large manipulations of timing, no study to date has ever directly examined the use of auditory feedback in speech production under the age of 4. Here we use a real-time formant perturbation task to compare the response of toddlers, children, and adults to altered feedback. Children and adults reacted to this manipulation by changing their vowels in a direction opposite to the perturbation. Surprisingly, toddlers' speech didn't change in response to altered feedback, suggesting that long-held assumptions regarding the role of self-perception in articulatory development need to be reconsidered.     

Effect of ambient temperatures during oocyte recovery on in vitro production of bovine embryos

Recovery of oocytes from ovaries collected at slaughter was carried out at three ambient temperatures (25 degrees, 30 degrees and 35 degrees C) to assess the effect on subsequent embryonic production in vitro. Oocytes recovered at each temperature were thereafter maintained at temperatures > or =35 degrees C as they were subjected to in vitro maturation, fertilization and culture (IVM/IVF/IVC). The oocytes and resulting embryos within each temperature group were subsequently evaluated for their rates of fertilization, cleavage and development to blastocysts, as well as for the number of cells/blastocyst. The results demonstrate that exposure of cumulus-ocyte-complexes (COCs) to temperatures below 35 degrees C during oocyte recovery is detrimental to optimal embryo production. Although the fertilization and cleavage rates of oocytes recovered at temperatures below 35 degrees C were not significantly lower than that of the controls, the percentage of oocytes recovered at 35 degrees C that developed to the blastocyst stage following fertilization and culture (33.7%) was significantly greater than those from oocytes recovered at either 25 degrees C (22.4%) or 30 degrees C (19.5%). The mean numbers of blastomeres/embryo were significantly lower in embryos derived from oocytes collected at either 25 degrees or 30 degrees compared with those collected at 35 degrees C. The results of this study suggest that exposure of COCs to temperatures below 35 degrees C during oocyte recovery may significantly decrease both the quantity and quality of embryos produced by in vitro methods.     

Identification of coiled bodies inBrassica napus nuclei during embryogenesis and early germination

Summary Nucleolus-associated bodies characterize interphase nuclei of many plant species. The recent demonstration that such bodies contain small nuclear ribonucleoproteins as well as coilin clearly indicates that they belong to a larger family of nuclear structures, known as coiled bodies, that have been intensively studied in a variety of animal cell types. In a previous work, we have shown that coiled bodies were present in close association with the nucleolus inZea mays dry seeds as well as during subsequent stages of germination. This study reveals that similar nuclear structures were also present duringBrassica napus embryogenesis starting at the torpedo stage and that they were, likewise, generally located on the nucleolar surface. As in the case ofZ. mays, coiled bodies were observed in cells of dry seeds as well as in those of early germinating tissues. These bodies were labelled with monoclonal antibody K121, an antibody reacting with the unique 5-terminal cap structure containing 2,2,7-trimethylguanosine that characterizes small nuclear RNAs. Owing to their intimate association with the nucleolus in all stages studied, the possibility is considered that, in these plant cells, coiled bodies are assembled on an organizer element located within this organelle.Abbreviations BSA bovine serum albumin - IgM immunoglobulin M - NAB nucleolus-associated body - NAC nucleolus-associated chromatin - PBS phosphate-buffered saline - snRNA small nuclear ribonucleic acid - snRNP small nuclear ribonucleoprotein     

Direct sequencing and PCR mapping of integrons reveals multiple class 1 integrons in the multiresistant strain Enterobacter cloacae SCH88040794

We have characterized the variable region of three integrons found in the multiresistant strain Enterobacter cloacae SCH88040794, using polymerase chain reaction and direct sequencing of amplicons. The first integron has the gene cassette arrangement dfrAI-aadA1 in its variable region and the second aadB-oxa9. The third integron is In40 (aacA4-qacF-cmlB-oxa9), which has recently been described. The multiresistance expressed by this strain to amikacin, gentamicin, trimethoprim, sulfonamides, oxacillin, chloramphenicol and quaternary ammonium compounds is due, at least in part, to these three integrons.