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PubMed2002

Lyssavirus P gene characterisation provides insights into the phylogeny of the genus and identifies structural similarities and diversity within the encoded phosphoprotein.

A comprehensive phylogenetic analysis of the Lyssavirus genus, employing P gene sequences from 128 isolates recovered globally, is presented. While confirming prior suggestions of the genetic distinctness of the Australian bat lyssaviruses, these data also revealed a clear division within the rabies virus clade (Genotype 1) between globally distributed viruses circulating predominantly in canid species (subgroup 1-1), and American strains harbored by both chiropteran and terrestrial hosts (subgroup 1-2). Nucleotide substitution patterns within the P locus suggested differential selection operating along the length of the open reading frame (ORF) between rabies viruses of these two subgroups. Comparison of the deduced primary sequences of the encoded phosphoproteins of all isolates provided insights into the product's structural organization. Two conserved (CD1,2) and two variable (VD1,2) domains were evident; high variation in the VD2 region was reflected by differences in hydropathic profiles. Only two of five serine residues reported to function as phosphate acceptors in the P protein of the rabies challenge virus standard (CVS) strain were absolutely conserved; similarly, out of four internal methionines reported to direct internal translation initiation of the CVS strain to produce N-terminally truncated P proteins, only Met(20) was universally retained. In contrast, two sequence motifs, one believed to confer binding to the cytoplasmic dynein light chain LC8, and a lysine-rich sequence probably contributing to N protein binding, were conserved throughout the genus. Most rabies viruses of the carnivora (1-1) contain a potential C ORF in alternate frame to that of P, a feature limited or absent in most other isolates of the genus, an observation interpreted with consideration to the predicted course of lyssavirus evolution.

Amino Acid Sequence↗
PubMed2005

The virus-immunity ecosystem.

The ecology of pathogenic viruses can be considered both in the context of survival in the macro-environments of nature, the theme pursued generally by epidemiologists, and in the micro-environments of the infected host. The long-lived, complex, higher vertebrates have evolved specialized, adaptive immune systems designed to minimise the consequences of such parasitism. Through evolutionary time, the differential selective pressures exerted variously by the need for virus and host survival have shaped both the "one-host" viruses and vertebrate immunity. With the development of vaccines to protect us from many of our most familiar parasites, the most dangerous pathogens threatening us now tend to be those "emerging", or adventitious, infectious agents that sporadically enter human populations from avian or other wild-life reservoirs. Such incursions must, of course, have been happening through the millenia, and are likely to have led to the extraordinary diversity of recognition molecules, the breadth in effector functions, and the persistent memory that distinguishes the vertebrate, adaptive immune system from the innate response mechanisms that operate more widely through animal biology. Both are important to contemporary humans and, particularly in the period immediately following infection, we still rely heavily on an immediate response capacity, elements of which are shared with much simpler, and more primitive organisms. Perhaps we will now move forward to develop useful therapies that exploit, or mimic, such responses. At this stage, however, most of our hopes for minimizing the threat posed by viruses still focus on the manipulation of the more precisely targeted, adaptive immune system.

Animals↗
PubMed1996

Suppression of beta-oxidation restores pyruvate inhibition of pyruvate dehydrogenase kinase in starved rat heart.

Kinetic behaviour of rat heart pyruvate dehydrogenase kinase (PDHK alpha) was studied in the multi-enzyme complex (PDC) contained in two preparations: mitochondria (mPDC) and a high speed pellet of Triton-extracted tissue (hPDC). Two parameters were evaluated: Vav, related to Vmax, and Fractional Pyruvate Inhibition (FPI). Starvation of rats for 48 h led to a rise in Vav and a fall in FPI. Injection into starved rats of agents which reduce beta-oxidation of fatty acids restored, in succession, FPI and then Vav, of hPDC, to levels found in hPDC from fed animals. In vitro incubation at 30 degrees C of hPDC from starved animals restored FPI, but not Vav to 'fed' values; both were restored during in vitro incubation of mPDC from starved animals within the same time frame as in the in vivo experiments. A sharp increase of FPI, but not Vav, of hPDC from both fed and starved rats was observed in later experiments. This could have been due to differential selection of the two genes for isoenzymes of PDHK alpha proposed by other workers.

Animals↗
PubMed1978

Alcohol dehydrogenase polymorphism in populations of Drosophila melanogaster. II. Relation between ADH activity and adult mortality.

Eight Drosophila melanogaster strains, seven homozygous for AdhF alleles and one for an Adh-null mutant, were compared for ADH activity in males and adult mortality on ethanol-supplemented food. The strains differed considerably in these qualities. A positive correlation was found between ADH activity and LD50. The relevance of this finding is discussed in relation to the differential selection acting on Adh genotypes kept on ethanol-supplemented food.

Alcohol Oxidoreductases↗
PubMed1979

Biochemical properties of esterase 6 in Drosophila melanogaster.

Biochemical properties of esterase 6 in Drosophila melanogaster were investigated using partially purified preparations from three genotypes, 1/1, 1/2, and 2/2. The molecular weight of the enzyme is estimated to be about 90,000, and treatment with sodium dodecylsulfate cleaves the enzyme into four units with a molecular weight of about 22,000. The activity toward 28 naturally occurring esters was assayed and shown to vary considerably with substrate, the 1/1 preparation having in general higher activity than 1/2 and 2/2, which were very similar. Heat sensitivity, the effect of metal ions, and the effects of the presence or absence of an end product were also studied. The differences demonstrated between allozymes would allow considerable scope, under appropriate conditions, for differential selection to operate between genotypes.

Animals↗
PubMed1995

Do Australian women have greater spinal bone density than North American women?

The interpretation of bone mineral densitometry results for a particular individual relies on valid reference data from a representative population sample. To establish local reference data, 411 Australian female volunteers had bone mineral densitometry performed at a single medical centre at the proximal femur and lumbar spine using a Hologic QDR 1000-W dual-energy X-ray absorptiometer. These data were compared with reference material from North American women compiled by Hologic. The Australian volunteers had, on average, 7% greater bone mineral density at the lumbar spine for the age range 25-55 years. Possible explanations for this include an actual population difference or the presence of a differential selection bias between the two samples.

Adolescent↗
PubMed1979

Optical demonstration of Chlamydiae in cell cultures by means of fluorochrome 33,258 H.

Fluorochrome 33,258 H, a bisbenzimidazole, was employed for demonstrating Chlamydiae in cell cultures, and proved to be particularly suitable for illustrating the unique intracellular reproduction processes of these organisms. The staining procedure is simple and permits a selective differentiation of chlamydial inclusions and their developmental processes in the cell. Contrary to other staining methods, all stages of the chlamydial reproduction cycle can be illustrated thus permitting the early demonstration of Chlamydiae in the cell. The procedure is suitable not only in experimental investigations on Chlamydiae but also in clinical diagnostics.

Cell Differentiation↗
PubMed1989

Amphibian albumins as members of the albumin, alpha-fetoprotein, vitamin D-binding protein multigene family.

The Xenopus laevis 68-kd and 74-kd albumin amino acid sequences are examined with respect to their relationship to the other known members of the albumin/alpha-fetoprotein/vitamin D-binding protein gene family. Each of the three members of this family presents a unique pattern of conserved regions indicating a differential selective pressure related to specific functional characteristics. Furthermore, an evolutionary tree of these genes was deduced from the divergence times calculated from direct nucleotide sequence comparisons of individual gene pairs. These calculations indicate that the vitamin D-binding protein/albumin separation occurred 560-600 million years (Myr) ago and the albumin/alpha-fetoprotein divergence 280 Myr ago. This observation leads to the hypothesis according to which the albumin/alpha-fetoprotein gene duplication occurred shortly after the amphibian/reptile separation. Consequently, and unlike mammals, amphibians and fishes should lack an alpha-fetoprotein in their serum at larval stages, which is consistent with a recent analysis of serum proteins in Xenopus laevis larvae. This hypothesis now will have to be tested further in additional lower vertebrates.

Albumins↗
PubMed1985

Holozygosity for sex-linked genes in males of the termite Incisitermes schwarzi.

The termite Incisitermes schwarzi has multiple sex chromosomes that have arisen by repeated translocations between autosomes and previously existing sex chromosomes. Two sex-linked allozyme loci--Acp-1 and Est-3--are holozygous, not hemizygous, in males (the heterogametic sex). Both loci show less than 1% crossing-over between X and Y chromosomes, and alleles of both are in marked disequilibrium with respect to X vs Y linkage. The two loci assort independently in female meiosis, indicating that they lie on different sex chromosomes. But they are tightly linked in male meiosis because of nonrandom assortment of the multiple X and Y chromosomes in males of this species. The findings of holozygosity and strong linkage disequilibrium suggest that differential selection in the two sexes at or near these loci may be responsible for the establishment of the translocations in this species. The existence of active Y-linked alleles also suggests that the translocations may have occurred recently.

Acid Phosphatase↗
PubMedDate not supplied

Studies of the role of the central nucleus of the amygdala in controlling cardiovascular functions.

Studies on cats anesthetized with a mixture of chloralose and Nembutal addressed the effects of high-frequency stimulation (100 impulses/sec) of the central nucleus of the amygdala on bioelectrical activity in two postganglionic sympathetic nerves-the inferior cardiac nerve and the vertebral branch of the stellate ganglion, which innervate the coronary vessels and the vessels of the anterior thorax respectively. The central nucleus of the amygdala was found to have differential, selective effects, in most experiments producing increases in the amplitude of integrated activity in the inferior cardiac nerve and decreases in the amplitude of biopotentials in the vertebral nerve. In a few experiments, a second type of modulation of the activities of these two postganglionic nerves was seen, with selective inhibition of activity in the inferior cardiac nerve and an accompanying increase in activity in the vertebral nerve. Stimulation of the central nucleus of the amygdala induced significant increases in systemic arterial blood pressure. The role of the central nucleus of the amygdala in the development of experimental neurogenic hypertension was studied in a series of chronic experiments on rats; these established that rats subjected to bilateral electrolytic lesioning of the central nucleus of the amygdala prevented the development of neurogenic hypertension induced by daily imposition of stress for four weeks for induction of operant aversive conditioned reflexes, which was not the case in control rats. The role of the central nucleus of the amygdala in the regulation of vascular tone is discussed.

Amygdala↗
PubMed1999

Morphology and immunohistochemistry of rat aortic grafts.

Allotransplantation (TPL) of the abdominal aortic segments of BN donors was performed in 32 Lewis recipients with or without cyclosporin A (CyA) immunosuppression, and the vascular changes were compared to those of 10 syngeneic grafts (Lewis-->Lewis) and to the autologous rat aortae. The vessels were examined 2, 3, 4 and 5 months post TPL by light microscopy, the thickness of intima and media was measured morphometrically and the cell infiltration of adventitia and intima was assessed semiquantitatively. Thirty-six aortae were examined by three-step enzyme immunohistochemistry (proof of selected differentiation, proliferation, cytoskeletal and connective tissue matrix antigens). The adventitia displayed an intense focal and scattered mononuclear cell infiltration; it was more discrete and focal in the intima. This cellularity persisted in the allografts but disappeared from the intima and was reduced in the adventitia of the isografts after four and five months. Disseminated ED1+ activated macrophages were the most prominent population of infiltrates whereas modest numbers of adventitial ED2+ tissue macrophages remained constant throughout the intervals examined. CD4+ cells (focal and scattered) outnumbered (roughly twice) the scattered CD8+ lymphocytes; both these types were rare in the intima. Leukocyte invasion of the media was lacking (except for scarce isolated CD8+ cells in some allografts). In syngeneic grafts the smooth muscle cells (SMC) of media remained intact and the intimal thickening was slight to absent (about 5 microns) four and five months post TPL. On the other hand, the allograft media underwent severe destructive changes (karyolysis, depletion of alpha-SMC actin, focal calcification and general thinning without rupture or aneurysm). The prominent allograft intimal thickening (70-80 microns) was due to the proliferation of longitudinally oriented myointimal cells (alpha-SMC actin, FD2, PCNA and Ki67+) and an increase in matrix substance (strong metachromasia and positivity of chondroitin-sulfate proteoglycan). The deposition of lipids remained discrete, without atheromatous plaques and mural thrombosis. All changes were comparable in CyA-treated and untreated animals. Thus the main lesions of the allografts were (i) persistent mononuclear infiltration chiefly in adventitia, (ii) destruction of medial SMC, and (iii) intimal thickening by proliferation of myointimal cells. At the postTPL intervals examined the proliferation and intimal migration of medial SMC were not apparent and a morphological correlate of significant anti-medial-SMC cytotoxic attack was lacking.

Animals↗
PubMed1997

Annexin gene structures and molecular evolutionary genetics.

Annexins provide an exemplary model for studying the pattern and process of molecular evolution in multigene families. Their related gene structures, broad dispersal in eukaryotic genomes and abundant coding sequences permit a phylogenetic reconstruction of their genetic history. The emerging picture is one of prolific expansion by gene duplication to more than 27 paralogous subfamilies that have undergone steady sequence divergence, speciation and differential selection. Homologous recombination via the common tetrad of internal repeats has, nevertheless, strictly preserved this core structure for over 1200 million years, implying a basic functional role. The existence of multiple annexins with unique 5' coding and regulatory regions has facilitated their adaptation to the varying ontogenetic and cell-specific needs of diverse organisms. Computational and cladistic sequence analyses have permitted the determination of original gene duplication dates and mutation rates for the ten known vertebrate annexins. Molecular genetic and evolutionary studies of annexins can help to define their structure-function relationships elucidate their individual physiological roles and ultimately link them to hereditary phenotypes.

Annexins↗
PubMed2006

The complete mitochondrial genome of the entomopathogenic nematode Steinernema carpocapsae: insights into nematode mitochondrial DNA evolution and phylogeny.

We determined the complete sequence of the mitochondrial DNA of the entomopathogenic nematode Steinernema carpocapsae and analyzed its structure and composition as well as the secondary structures predicted for its tRNAs and rRNAs. Almost the complete genome has been amplified in one fragment with long PCR and sequenced using a shotgun strategy. The 13,925-bp genome contains genes for 2 rRNAs, 22 tRNAs, and 12 proteins and lacks an ORF encoding ATPase subunit 8. Four initiation codons were inferred, TTT, TTA, ATA, and ATT, most of the genes ended with TAA or TAG, and only two had a T as an incomplete stop codon. All predicted tRNAs showed the nonconventional secondary structure typical of Secernentea. Although we were able to fold the sequences of trnN, trnD, and trnC into more conventional cloverleaf structures after adding adjacent nucleotides, northern blot experiments showed that the nonstandard tRNAs are actually expressed. Phylogenetic and comparative analyses showed that the mitochondrial genome of S. carpocapsae is more closely related to the genomes of A. suum and C. elegans than to that of Strongyloides stercoralis. This finding does not support the phylogeny based on nuclear small subunit ribosomal DNA sequences previously published. This discrepancy may result from differential reproductive strategies and/or differential selective pressure acting on nuclear and mitochondrial genes. The distinctive characteristics observed among mitochondrial genomes of Secernentea may have arisen to counteract the deleterious effects of Muller's ratchet, which is probably enhanced by the reproductive strategies and selective pressures referred to above.

Animals↗
PubMed2006

Evidence for an early gene duplication event in the evolution of the mitochondrial transcription factor B family and maintenance of rRNA methyltransferase activity in human mtTFB1 and mtTFB2.

Most metazoans have two nuclear genes encoding orthologues of the well-characterized Saccharomyces cerevisiae mitochondrial transcription factor B (sc-mtTFB). This class of transcription factors is homologous to the bacterial KsgA family of rRNA methyltransferases, which in Escherichia coli dimethylates adjacent adenine residues in a stem-loop of the 16S rRNA. This posttranscriptional modification is conserved in most metazoan cytoplasmic and mitochondrial rRNAs. Homo sapiens mitochondrial transcription factor B1 (h-mtTFB1) possesses this enzymatic activity, implicating it as a dual-function protein involved in mitochondrial transcription and translation. Here we demonstrate that h-mtTFB2 also has rRNA methyltransferase activity but is a less efficient enzyme than h-mtTFB1. In contrast, sc-mtTFB has no detectable rRNA methyltransferase activity, correlating with the lack of the corresponding modification in the mitochondrial rRNA of budding yeast. Based on these results, and reports that Drosophila melanogaster mtTFB1 and mtTFB2 do not have completely overlapping functions, we propose a model for human mtDNA regulation that takes into account h-mtTFB1 and h-mtTFB2 likely having partially redundant transcription factor and rRNA methyltransferase functions. Finally, phylogenetic analyses of this family of proteins strongly suggest that the presence of two mtTFB homologues in metazoans is the result of a gene duplication event that occurred early in eukaryotic evolution prior to the divergence of fungi and metazoans. This model suggests that, after the gene duplication event, differential selective pressures on the rRNA methyltransferase and transcription factor activities of mtTFB genes occurred, with extreme cases culminating in the loss of one of the paralogous genes in certain species.

Animals↗
PubMed2005

A new splicing acceptor site and poly(A)+ sequence signal within DQA1*0401 and DQA1*0501 mRNA 3'UTR contribute to increase the extraordinary diversity of mRNA isoforms.

In this paper, we have analysed the diversity of mRNA species generated by DQA1*0501 and DQA1*0401 alleles in homozygous B-lymphoblastoid cell lines. As we previously reported, six mRNA isoforms that differ in the 3'UTR have been identified in these cells. This diversity of mRNA species results both from the alternative use of two acceptor spliced sites and the differential selection of two poly(A)+ sequence signals by the processing machinery. In this report we describe a new acceptor sequence signal that allows generation of a new alternative spliced mRNA species. This acceptor sequence signal was also present in all of the seven DQA1 homozygous cell lines analysed. In addition, we have identified a previously undetected, non-conventional but functional, poly(A)+ sequence signal that lacks an identifiable AATAAA hexamer, one of the most important element of the core. This sequence signal allows the generation of two additional mRNA isoforms both in DQA1*0501 and DQA1*0401 homozygous cell lines but not in the others. We show that DQA1*0501 and DQA1*0401 primary transcripts can be processed into nine mRNA isoforms that differ in the 3'UTR. Finally, we summarized all the DQA1 mRNA species deriving from DQA1*0101, DQA1*0102, DQA1*0103, DQA1*0201, DQA1*0301, DQA1*0401 and DQA1*0501 alleles and shown in B-lymphoblastoid cell lines.

3' Untranslated Regions↗
PubMed2005

Transcriptional profiling of skeletal muscle tissue from two breeds of cattle.

We used a 9.6 K cattle muscle/fat cDNA microarray to study gene expression differences between the longuissimus dorsi (LD) muscle of Japanese Black (JB) and Holstein (HOL) cattle. JB cattle exhibit an unusual ability to accumulate intramuscular adipose tissue with fat melting points lower than that in other breeds. The LD biopsies from three JB (Tajima strain) and three HOL animals were used in this breed comparison. Seventeen genes were identified as preferentially expressed in LD samples from JB and seven genes were found to be expressed more highly in HOL. The expression of six selected differentially expressed genes was confirmed by quantitative real-time PCR. The genes more highly expressed in JB are associated with unsaturated fatty acid synthesis, fat deposition, and the thyroid hormone pathway. These results are consistent with the increased amounts and proportions of monounsaturated fatty acids observed in the muscle of JB animals. By discovering as yet uncharacterized genes that are differentially regulated in this comparison, the work may lead us to a better understanding of the regulatory pathways involved in the development of intramuscular adipose tissue.

Animals↗
PubMed2003

Gender-specific floral and physiological traits: implications for the maintenance of females in gynodioecious Lobelia siphilitica.

A common gender dimorphism in angiosperms is gynodioecy, in which hermaphrodites and females co-occur. Females are at an inherent disadvantage because they can transmit their genes only through ovule production. One mechanism by which females can compensate for the loss of male function is by producing more seeds than hermaphrodites. As such, females should: (1) increase resource uptake to support higher seed production; and (2) allocate resources saved by the loss of male function to seed production. To test this hypothesis, we measured physiological and floral traits of gynodioecious Lobelia siphilitica, controlling for both environmental and genetic variation through a comparison of greenhouse-grown siblings. Pre-reproductive females had 14% higher area-based (Z=2.14; P=0.04) and 32% higher mass-based (Z=1.96; P=0.05) photosynthetic rate than hermaphrodites, suggesting that they have increased carbon acquisition by altering photosynthetic physiology. Female L. siphilitica produced flowers with 4-8% smaller corollas than hermaphrodites (all P<0.05), suggesting that females allocate resources away from floral structures used for pollinator attraction. The genetic correlation between genders for four floral and four physiological traits was significantly less than one but greater than zero, indicating that the evolution of gender dimorphism in response to sex-differential selection will be constrained. The allocation of resources saved by the loss of male function has been viewed as the most important mechanism allowing females of gynodioecious species to support higher seed production. Our data suggest that increased resource acquisition by females at pre-reproductive stages can also contribute to the maintenance of gender dimorphism in gynodioecious species.

Analysis of Variance↗
PubMed2006

Structure based studies of the adaptive diversification process of congerins.

The isoforms of a fish galectin, congerins I and II, have several features that make them suitable for a study of accelerated process of molecular diversification based on 3D structures: They have been generated by a gene duplication, and still maintain 47% amino acid sequence identity to each other. Their genes show very high K A: /K S: ratio, and are though to be components of fish defense system. The crystal systems for a high-resolution analysis are known for both proteins. A series of works with biochemistry, molecular biology, and X-ray crystallography techniques have suggested that the two proteins might have evolved under differential selection pressures. Congerin I appeared to be a stabilized version of galectin-1. Congerin II was shown to be adapted to a new carbohydrate-ligand. The 3D structures of the wild type and mutant proteins have revealed the probable cause and consequence of the selection pressure responsible for the diversification of congerins.

Adaptation, Physiological↗