Convergent evolution of cysteine residues in sperm protamines of one genus of marsupials, the Planigales

A characteristic feature of the sperm P1 protamines of eutherian mammals is the constant presence of six to nine cysteine residues per molecule. During spermiogenesis these residues become oxidized to form a three-dimensional network of disulfide bridges between, and within, protamine molecules in the sperm chromatin. This covalent cross linking strongly stabilizes eutherian sperm nuclei. In contrast, protamines sequenced from teleost fish, birds, monotremes, and marsupials all lack cysteine residues and their sperm nuclei, without the stabilizing cross links, are easily decondensed in vitro. We have now found that one genus of tiny, shrewlike dasyurid marsupials, the Planigales, possess P1 protamines containing five to six cysteine residues. These residues appear to have evolved since the divergence of Planigales from other members of the family Dasyuridae, such as the marsupial mouse, Sminthopsis crassicaudata. We believe this constitutes a case of convergent evolution in a subfamily of dasyurid marsupials toward the cysteine-rich eutherian form of sperm protamine P1.      

Interaction of singlet oxygen with DNA and biological consequences.

To study the interaction of singlet oxygen (1O2) with DNA and the biological consequences of 1O2-induced DNA damage, we used the thermodissociable endoperoxide of 3,3'-(1,4 naphthalidene) dipropionate (NDPO2) as a generator of free 1O2 in reactions with (1) 2'-deoxynucleoside 3'-monophosphates (dNps), (2) an oligonucleotide (16-mer) having one deoxyguanine (dG), (3) native and denaturated rat kidney DNA and (4) single-stranded (ss) and double-stranded (ds) bacteriophage M13mp10 DNA. Using both anion exchange and reversed phase HPLC and 32P-postlabeling analyses, it was found that exposure of the various dNps to chemically generated 1O2 led to a detectable reaction with dGp and not with dAp, dCp, d5mCp or Tp. The reaction with dGp led to degradation of this nucleotide and the formation of a large number of reaction products, one of which could be identified as 7-hydro-8-oxo-2'-deoxyguanosine 3'-monophosphate (8-oxo-dGp). A second product could tentatively be identified as a formamido pyrimidine derivative of dGp (Fapy-dGp). When ss DNA, ds DNA or the oligonucleotide were exposed to 1O2, the formation of 8-oxo-dG could also be demonstrated. With the oligonucleotide, we found a so far unidentified reaction product. Under the same reaction conditions the yield of 8-oxo-dG was about 8-fold higher in ss DNA than in ds DNA. In ss DNA 8-oxo-dG seemed to be a more prominent product than in the case of reaction of 1O2 with free dGp. Reaction of 1O2 with ss or ds M13mp10 DNA led to biological inactivation of these DNAs, ss DNA being at least 100-fold more sensitive than ds DNA. It could be concluded that inactivation of the ss DNA must be largely due to 1O2-induced DNA lesions other than 8-oxo-dG. In agreement with the observed preferential reaction of 1O2 with dG most of the so far sequenced mutations, induced by 1O2 in a 144 bp mutation target sequence inserted in the lacZ alpha gene of ss or ds M13mp10 DNA, occurred at a G or G/C base pair respectively. A preference for G(C) to T(A) transversions can be observed for which 8-oxo-dG might have been responsible. In ss DNA a significant number of the mutations are characterized by the fact that a G is deleted.     

Biological relevance of gamma-ray-induced alkali-labile sites in single-stranded Dna in aqueous solutions.

Gamma-irradiation in single-stranded phiX174 DNA in aqueous solution in the presence of oxygen produces at least two types of alkali-labile site. One is lethal and gives rise to single-strand breaks by treatment with alkali. The other is non-lethal, but is converted to lethal damage by alkali. The effect of alkali is dependent on temperature. This dependence is different for both types of alkali-labile site.     

Maximum Annual Potential Yields of <Emphasis Type="Italic">Salix miyabeana</Emphasis> SX67 in Southern Quebec and Effects of Coppicing and Stool Age

Aboveground biomass yields of short rotation cultures (SRC) of willow can vary substantially depending on site quality. Among others, aboveground biomass yields depend on climatic conditions, soil properties, age of the SRC, and number of harvesting cycles. In this study, we investigated the effects of coppicing on growth variables (i.e., largest basal stem, height, and aboveground biomass) at ten SRC of Salix miyabeana SX67 established on various soils in southern Quebec. More than 1100 shrubs with stool ages varying between 1 and 15 years were measured. Strain analysis was carried out to calculate past annual aboveground productivities, and maximum annual yield potential was quantified at each site. Annual growth rates were highly variable and depended on site and coppicing history. To achieve optimal stool development and aboveground yields, two to three growing seasons following coppicing were necessary for sandy and clayey sites, respectively. The delays for reaching maximum yields were shortened when soil cation exchange capacity was dramatically low and were prolonged when soil was physically restricting stool development. This lag influenced the total yield of the first rotation and also modulated the magnitude of the increase of aboveground biomass that is generally observed in the second rotation. To increase yields in southern Quebec, our results suggest that it is preferable to extend the length of the first rotation instead of coppicing at the end of the first growing season after establishment.     

Yersiniosis in children

Sixty-five strains of Yersinia enterocolitica were isolated from stool specimens obtained from 35 patients over a 12-month period. The microbiologic characteristics and drug sensitivities are reported and the clinical patterns of disease associated with the organism are described. Gastroenteritis affecting infants and young children is the most frequent manifestation. The data for 1972 show the same epidemiological trend as in preceding years.     

Surface membrane differentiation of hemopoietic cells as observed by radioactive labeling

Bone marrow cells from normal rats were separated by velocity sedimentation into three distinct populations corresponding to granulocytes, lymphocytes and reticulocytes. Cells from each population were surface labelled via the lactoperoxidase radioiodination or the tritiated borohydride reduction. Distinct labeling patterns were observed on SDS-PAGE for each cell population. Separation of bone marrow cells from anemic rats injected with TAB vaccine led to four populations corresponding to successive stages of erythroid cell maturation. Labelled protein patterns were not in this case as different from one population to the other, except for one species which increased in intensity with the degree of maturation. The tritiated glycoprotein profiles show a shift from high to low molecular weight species during the process of maturation.     

Tetraspanin Proteins Regulate Membrane Type-1 Matrix Metalloproteinase-dependent Pericellular Proteolysis

Membrane type-1 matrix metalloproteinase (MT1-MMP) supports tumor cell invasion through extracellular matrix barriers containing fibrin, collagen, fibronectin, and other proteins. Here, we show that simultaneous knockdown of two or three members of the tetraspanin family (CD9, CD81, and TSPAN12) markedly decreases MT1-MMP proteolytic functions in cancer cells. Affected functions include fibronectin proteolysis, invasion and growth in three-dimensional fibrin and collagen gels, and MMP-2 activation. Tetraspanin proteins (CD9, CD81, and TSPAN2) selectively coimmunoprecipitate and colocalize with MT1-MMP. Although tetraspanins do not affect the initial biosynthesis of MT1-MMP, they do protect the newly synthesized protein from lysosomal degradation and support its delivery to the cell surface. Interfering with MT1-MMP-tetraspanin collaboration may be a useful therapeutic approach to limit cancer cell invasion and metastasis.