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M Westerman

Publications and source records attributed to M Westerman.

At least 37 records · Page 2Linked to original sources
PubMed1996

Were bowerbirds part of the New Zealand fauna?

Bowerbirds (Ptilonorhynchidae) have previously been considered to be confined to the Australo-Papuan continental plate. We provide molecular evidence that the extinct New Zealand Piopio Turnagra capensis is, in fact, a bowerbird. Such a finding is surprising on biogeographical grounds. However, recent molecular evidence on the relationships of the New Zealand moas and kiwis with the Australo-Papuan flightless birds suggests the need for a reassessment of current views on the origins of New Zealand's fauna.

Animals↗
PubMed1995

Molecular phylogeny and evolution of marsupial protamine P1 genes.

We report the DNA sequences of protamine P1 genes and flanking regions from 21 mammalian species, including representatives of all extant marsupial orders. The protamine P1 locus in marsupials displays highly conserved 5' and 3' flanking sequences, as well as a highly variable intron. Marsupial protamines examined are distinct from those of eutherian mammals in lacking cysteine residues, a feature that may be correlated with lower stability of marsupial sperm nuclei during chromatin condensation. Phylogenetic analysis of protamine sequences leads to the following conclusions: (i) the microbiothere Dromiciops is part of a clade that includes dasyurids, Notoryctes and diprotodontians but not bandicoots; (ii) dasyurids are the closest living relatives of Notoryctes; (iii) macropodids, phalangerids and pseudocheirids form a clade apart from the phascolarctids; and (iv) the closest living relatives of caenolestids are didelphids.

Amino Acid Sequence↗
PubMed1995

The evolution of protamine P1 genes in dasyurid marsupials.

We report the complete DNA sequences of the protamine P1 gene and flanking regions for 13 species of the marsupial family Dasyuridae. The structure of the protamine locus is conserved in dasyurids and consists of two exons (of lengths 142-151 and 47 bp) separated by an intron (208-240 bp). A key feature of the dasyurid intron is a 38-40 bp duplication found in all species examined to date. This duplication apparently predates the radiation of modern dasyurid lineages and may be homologous to a similar feature in the marsupial mole (Notoryctes). Sequences from a species of Planigale demonstrate that this genus is unique among marsupials in possessing cysteine residues in its protamine P1 molecules. Cysteines may provide enhanced chemical stability for condensed sperm nuclei, a physiological feature that would converge on the common eutherian pattern. Phylogenetic analysis of the protamine genes yields a tree that is largely congruent with previous molecular systematic studies in two areas: (1) There are three main dasyurid lineages corresponding to the Sminthopsinae. Dasyurinae, and Phascogalinae; (2) Dasyurinae and Phascogalinae are sister groups. This study is the first estimate of dasyurid relationships based on a nuclear DNA sequence.

Amino Acid Sequence↗
PubMed1995

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.

Amino Acid Sequence↗
PubMed1995

Imbalance of immune responses in patients with chronic and widespread fungal skin infection.

Fungal infections of the skin are caused by dermatophyte fungi. Infections can be acute and inflammatory or chronic and non-inflammatory; it is believed that cell-mediated immunity is the cornerstone of host defence and is instrumental in the eradication of the infection. We describe here parameters of the immune response of a group of patients who although not immunocompromised, suffered from widespread and chronic infections. All patients lacked a specific delayed-type hypersensitivity (DTH) response; however, their in vitro lymphocyte proliferation in response to Trichophyton rubrum extract and to other fungal antigens was normal. The patients were not atopic by clinical history, and yet had high levels of non-specific IgE and of T. rubrum-specific IgG4. Taken together, the results of this study suggest that the group of patients studied suffered from an immune imbalance which has characteristics of a Th2-type response.

Adult↗
PubMed1993

The influence of growth medium on the yield of X-ray-induced chromatid exchanges in the presence and absence of aphidicolin.

The frequency of exchanges in JU56 cells irradiated in the G2 phase in the presence and absence of the polymerase inhibitor aphidicolin (APC), and in the presence of a range of concentrations of cysteine was measured. It was found that in the absence of cysteine, incubation for 2 h with APC had no effect on the yield. Addition of cysteine at concentrations of 50-250 mg/l reduced the frequency of exchanges, and at these concentrations the frequency was increased by incubation with APC. At higher concentrations, the yield was reduced and incubation with APC did not elevate it. In following experiments, it was found that incubation with cysteine for a period of longer than 10 minutes was necessary before APC affected the yield of exchanges.

Animals↗
PubMed1990

Erythrocyte membrane abnormalities in sickle cell disease.

A large fraction of circulating sickle red cells contain one or more large vesicles which are not found in normal erythrocytes. These vesicles contain very high levels of Ca2+, and probably account for the long-known elevation of cellular Ca2+ in sickle cells. These vesicles contain the plasma membrane CaATPase and leak Ca2+ by a nitrendipine-sensitive pathway. The question of whether an abnormal endocytic process occurs in sickle cells which could give rise to these vesicles was examined using the nonspecific endocytic marker Lucifer yellow (LY). The kinetics of formation of LY-labeled endocytic vesicles in sickle cells includes a slow component which is not found in normal (or sickle) reticulocytes. In addition, the number of sickle cells in which endocytosis can be demonstrated with this nonspecific marker consistently exceeds the number which can be labeled with markers of the receptor-mediated endocytic process. The results suggest that a slow, abnormal endocytosis takes place in sickle cells which may be the source of the Ca2(+)-containing vesicles, and therefore of the elevated Ca2+ levels characteristic of the circulating cells in this disease.

Anemia, Sickle Cell↗
PubMed1987

Interspecies comparison of the highly-repeated DNA of Australasian Luzula (Juncaceae).

The woodrush genus Luzula is characterised by having holocentric chromosomes. DNA of nine related Australasian species shows similar satellite DNAs which re very similar in nucleotide sequence content and unit length. Differences between the repetitive DNAs are evident as either the presence or absence of particular restriction enzyme sites. Sequence variants have probably been introduced into the repeated DNA components of ancestral species and particular variants reamplified during the evolution of the genus. Sequence amplification appears to be restricted to sequences already present in the genome rather than the de novo generation of repeats. The evolution of highly-repeated DNA sequences dispersed throughout the holocentric chromosomes of Luzula thus appears to be very similar to that known in eukaryotes with the more normal monocentric chromosome organisation.

Biological Evolution↗
PubMed1985

Safety and efficacy of guanabenz in hypertensive patients with moderate renal insufficiency.

Eight hypertensive patients with moderate renal insufficiency were treated with gradually increasing oral doses of guanabenz acetate to a maximum dose of 8 mg BID. Patients' medications were titrated over 8 weeks. Once blood pressure control was achieved (seated diastolic blood pressure, 90 mmHg, or decrease of 10 mmHg from baseline values), drug dosages were maintained for up to a 12-week total treatment phase. Patients had significant reductions of blood pressure during treatment with guanabenz as compared to that during pretreatment levels. No changes in body weight or creatinine clearance were evident, as compared to baseline values. Our data suggest that guanabenz, in relatively small doses, can be used as safe and effective monotherapy of essential hypertension in patients with moderate renal insufficiency.

Blood Urea Nitrogen↗
PubMed1980

X-ray induced activity of N-ethylmaleimide-sensitive DNA polymerase in Chinese hamster cells.

Chinese hamster DDN cells have been exposed to low doses of X-irradiation (< 15 Gy). These doses have been shown to induce significant levels of repair replication. Levels of activity of DNA polymerase were subsequently measured in cells exposed in G1 phase of mitosis to 7.5 Gy of X-rays. Following exposure, the activity of this enzyme was observed to rise to a peak within 15 min post-irradiation, then decline and then rise again over a long period. The initial rise at least was found to be sensitive to inhibition by N-ethylmaleimide, a known inhibitor of DNA polymerase-alpha and DNA polymerase-gamma at the concentration used. It is therefore suggested that repair of X-ray-induced damage in these DON cells was at least in part dependent upon induced DNA polymerase activity and this may involve DNA polymerase-alpha or DNA polymerase-gamma, or both.

Animals↗
PubMed1975

Population cytology of the genus Phaulacridium.

Ten of the 27 populations of Phaulacridium marginale collected from South Island, New Zealand, during the 1973 meiotic season were polymorphic for extra heterochromatin. This was present either as B chromosomes or as super-numerary segments on the shortest autosomes. In some populations both polymorphisms were present simultaneously, sometimes at high frequencies. Three different types of B chromosome were seen; large telocentric, small telocentric and small metacentric isochromosomes though only one type was seen in any one population. Segments on the telocentric S9 and S10 chromosomes were located distally. On the S11 chromosome, however, the extra segment was present as a short arm, thus making the chromosome submetacentric. This latter situation is similar to that in the related species Ph vittatum. The frequency of B's in the OM population appeared to be stable over years and there was no indication of any meiotic "drive" or "drag" in the males. The frequency of occurrence of B chromosomes in a population correlated negatively with annual rainfall (low B frequencies in regions of high rainfall). Neither type of extra heterochromatin had any significant effect on either mean cell chiasma frequency or on log variance of this metric. Possible synergism between B's and segments is discussed from the preliminary analysis of the OM population. The probable origins and age of the polymorphisms are discussed in detail.

Animals↗
PubMed1975

Population cytology of the genus Phaulacridium. IV. Phaulacridium marginale (Walker)--the North Island populations.

Samples of Phaulacridium marginale were taken from the North Island of New Zealand, together with further samples from three South Island populations. Seven of the North Island populations were found to be polymorphic for a small telocentric B chromosome. In only one case was the B chromosome significantly associated with an increase chiasma frequency. All three South Island populations contained B chromosomes. Seven of the nine N.I. populations were also polymorphic for extra segments on the centric end of the S11 chromosome. In six of them this polymorphism co-existed with that for B'S. A new polymorphism was encountered in two populations. This was for a large block of heterochromatic material located at the centric end of one of the smaller medium-sized chromosomes which thus becomes acro- rather than telocentric. Tt would appear that the New Zealand grasshopper, Ph. marginale, is able to tolerate many different polymorphisms for extra heterochromatin. However, this ability is perhaps restricted to central populations. In this context, the high level of occurence of these polymorphisms in the North Island could be due to the better climatological conditions existing there compared to most of the South Island.

Aneuploidy↗