Search Results - (Author, Cooperation:M. Westerman)

2011-09-24

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Animals ; Biological Evolution ; Evolution, Molecular ; *Extinction, Biological ; *Fossils ; *Mammals/classification/genetics ; Molecular Sequence Data ; *Phylogeny

2018-07-27

American Society of Hematology (ASH)

0006-4971

1528-0020

Biology

Medicine

Red Cells, Iron, and Erythropoiesis

1365-2230

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

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.

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] HUMAN blood plasma contains at least two different enzymes capable of hydrolysing phenylacetate1'2. One of them is a cholinesterase, the other an aromatic esterase (arylesterase)3. The present studies deal with arylesterase and stem from our observation that the disodium ...

Electronic Resource

0027-5107

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Medicine

Electronic Resource

0027-5107

Aphidicolin ; Chromosomal exchange ; Cysteine ; Growth medium ; Polymerase

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Medicine

Electronic Resource

1432-0886

Springer Online Journal Archives 1860-2000

Biology

Medicine

Abstract Samples were taken from twenty three Australian mainland populations of the shorthorned grasshopper, Phaulacridium vittatum. Five of these populations were found to be polymorphic for B-chromosomes. The anaphase I segregation of the B-chromosome appeared to be random with respect to the X (contra Jackson and Cheung, 1967). The B-chromosomes did not appear to influence chiasma frequency in the population in which they were found.

Electronic Resource

1432-0886

Springer Online Journal Archives 1860-2000

Biology

Medicine

Abstract The pattern of response of chiasma frequency to X-irradiation has been studied in germ line cells of male imagines of Schistocerca gregaria. A correlation has been established between the observed changes in chiasma frequency of the L and M type bivalents and the time in the meiotic cycle at which the treatment is given. Two radio-sensitive periods have been identified in meiosis itself. At one (meiotic DNA synthesis) X-irradiation produces a decrease in chiasma frequency while at the other (leptotene-early zygotene) the treatment leads to an increase in chiasma frequency. Small bivalents however do not respond to treatment and form a single chiasma under all conditions.

Electronic Resource

1432-0886

Springer Online Journal Archives 1860-2000

Biology

Medicine

Abstract French populations of Chorthippus parallelus like those from Britain are polymorphic with respect to supernumerary segments on the M7 and S8 chromosomes. The pattern of polymorphism parallels that of British material on both morphological and behavioural grounds. It agrees also in its effect on mean cell chiasma frequency and the absence of any effect on between cell variance. Finally the agreement extends also to the distribution of karyotypes within populations, those of the S8 showing a Hardy-Weinberg distribution whereas those of the M7 show a deficiency of structurally heterozygous types. All these parallels imply a common origin for the British and French material, an origin which, so we must suppose, antedated the physical separation of Britain and France some 8,000 years ago.

Electronic Resource

1432-0886

Springer Online Journal Archives 1860-2000

Biology

Medicine

Abstract Symmetrical exchanges between non-homologous chromosomes were recovered following irradiation of germ-line cells of S. gregaria at different developmental stages. No X-Autosome exchanges were observed. It was found that the frequencies with which autosomes of the three size groups L, M and S participated in exchange agreed with the frequencies expected based on “effective” exchange lengths of polarized interphase chromosomes. All of the observed symmetrical exchanges were between euchromatic segments of the chromosomes and though many of the exchange points were close to the centromere, no exchanges were found with break points actually in the centric heterochromatin. None of the heterozygous symmetrical exchanges were seen to have an observable influence on the chiasma conditions of the cell.

Electronic Resource

1432-0886

Springer Online Journal Archives 1860-2000

Biology

Medicine

Abstract Twenty seven populations of the grasshopper Phaulacridium marginale were sampled from South Island, New Zealand. An analysis of the chiasma frequency data showed that populations differed significantly for this metric. The populations appeared to fall into two distinct size groups. Morphological measurements confirmed this and a reanalysis of the chiasma frequency data revealed that although the two groups differed significantly for both mean cell chiasma frequency and between cell variances, there was no difference between populations within a group. Analysis of climatological data suggests that the “larger” individuals show different environmental (habitat) preferences from the smaller, which are restricted to one region of South Island. The taxonomic status of Ph. marginale as a single species is called into question.

Electronic Resource

1432-1793

Springer Online Journal Archives 1860-2000

Biology

Abstract Eggs from two separate spawning stocks of the red drum Sciaenops ocellatus (Linnaeus) were hatched, and the larvae were reared in the laboratory for 2 wk under closely controlled conditions. Total RNA, DNA, and soluble protein were measured in each population daily in triplicate pooled samples of larvae from each of three tanks. Growth rate in mm d-1 was determined for each population at 2 d intervals. Growth rate explained 72 and 95% of the variation in the RNA:DNA ratios of the two populations individually, and 86% of the variation in the RNA:DNA ratio when data from the two populations were combined. The RNA:DNA ratio appeared to be most effective as an indicator of growth in rapidly growing larvae, and to lose some resolution when growth was intermittent. The rates of deposition of RNA, DNA, and protein into tissue were all highly correlated with growth rate and with each other. Mean population RNA:DNA ratios of red drum yolk-sac larvae decreased from Day 1 post-hatch until larvae initiated successful feeding behavior, and then increased steadily throghout the remainder of the experimental period. This pattern of change in the RNA:DNA ratios during the yolk-sac stage appears to be an intrinsic developmental pattern of red drum ontogeny. The lowest values for the RNA:DNA ratio were observed just prior to the initiation of feeding or during the “critical period”, indicating that red drum larvae experience a decrease in capacity for protein synthesis as they initiate feeding. Intrinsic variation in the RNA:DNA ratio during development suggests that caution be used when comparing the RNA:DNA ratios of yolk-sac larvae to a “critical ratio” calculated from Buckley's general model.

Electronic Resource

1432-1793

Springer Online Journal Archives 1860-2000

Biology

Abstract The teleost Fundulus heteroclitus (Linnaeus) employs a semilunar spawning strategy, whereby eggs deposited on a spring tide optimally hatch on the following spring tide. This spawning strategy constrains the development period to ≃2 wk, regardless of the mean water temperature, which varies throughout the species' range (Nova Scotia, Canada, to Florida, USA). We hypothesized that F. heteroclitus embryos would exhibit development-rate compensation among populations to ensure appropriate hatching during the spring tide. Development rates of embryos from Massachusetts and Florida were examined. Northern embryos had faster temperature-specific development rates than southern embryos, while data from the literature showed that embryos from Delaware have an intermediate development rate. Results from reciprocal hybrid crosses indicated that there may be a genetic basis for these differences. In addition, northern embryos were more cold-tolerant and southern embryos more heat-tolerant. Field studies showed that embryos in their local environments develop at similar rates despite large temperature differences. Embryos seldom, if ever, experience lethal temperatures in their native habitats, but would do so if exposed to the temperature regimes at the extreme ends of the species' range. Thus, F. heteroclitus populations along the Atlantic coast have specifically adapted their development rates and thermal tolerances to the local thermal regime.

Electronic Resource

1573-6857

Springer Online Journal Archives 1860-2000

Biology

Abstract 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 thant 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.

Electronic Resource

1573-6857

Springer Online Journal Archives 1860-2000

Biology

Abstract C-banding studies revealed the presence of C-positive regions interspersed amongst the euchromatin of the prophase holocentric chromosomes of Luzula flaccida. In-situ hybridization showed a highly-repeated DNA sequence to be located in clusters throughout the extended chromosomes. The interspersed distribution pattern of prophase C-bands and satellite DNA in L. flaccida is discussed in relation to those in organisms with monocentric chromosomes.

Electronic Resource

1573-6849

chromosome evolution ; fluorescence in-situ hybridization ; marsupials

Springer Online Journal Archives 1860-2000

Biology

Abstract In order to deduce the ancestral genome arrangement in the karyotypically diverse marsupial family Macropodidae, and to assess chromosome change in this family, chromosome-specific paints from the tammar wallaby (2n = 16) were hybridized to metaphase spreads from the two species proposed to represent the 2n = 22 ancestral karyotype, as well as species with derived 2n = 20 and 2n = 14 karyotypes. Identical patterns were observed in the two 2n = 22 species, from which the rearrangements to form the three derived karyotypes may be easily deduced to be 1, 3 and 4 different fusions, respectively. The identical Thylogale and Dorcopsis genomes may both be used to represent the pleisiomorphic macropodid chromosome complement. Variation in the X chromosome was also investigated by hybridizing an X-Y shared tammar wallaby 12-kb repeat element to chromosomes from the other four macropodid species, finding that it hybridized only to the most closely related species, and therefore is of recent origin.

Electronic Resource

0377-0486

Chemistry ; Analytical Chemistry and Spectroscopy

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Physics

The Raman spectra of erythrocyte membranes in water and D2O were analyzed to determine the percentage of protein and lipid contributions to the amide I spectral feature. The approach of Lippert et al. [J. Am. Chem. Soc. 98, 7075 (1976)] was modified to use circular dichroism data for protein conformations of erythrocyte membranes to determine the relative lipid and protein contributions to the 1660 cm-1 spectral feature. It was determined that 69 ± 15% of the measured peak intensity was due to the protein contribution. The implication of this data to the quantity of α-helix conformation in membrane protein of erythrocytes, and alternative approaches to determine protein conformation from Raman spectra are discussed.

2 Ill.

Electronic Resource

0377-0486

Chemistry ; Analytical Chemistry and Spectroscopy

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Physics

Raman spectra of erythrocyte membranes which were intact and erythrocyte membranes which were modified by extrinsic protein extraction procedures were examined. In all cases, there was no apparent correlation between protein extraction and membrane lipid fluidity. The extraction of the band 6 protein by 0.15 M NaCl but not 0.001 M NaDH raised the erythrocyte membrane α-helical content while the extraction of all extrinsic proteins by 0.1 M NaOH resulted in a decrease in protein α-helical content. The study shows that either peripheral protein extraction and/or salt solutions can modify the secondary structures of the remaining intrinsic membrane proteins.

2 Ill.

Electronic Resource