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PubMedDate not supplied

An ultrastructural study of development and reproduction in the nematode parasite Myzocytiopsis vermicola.

An isolate of Myzocytiopsis vermicola, a holocarpic parasite of Rhabditis nematodes, was studied with transmission electron microscopy (TEM) to follow development during infection, asexual and sexual reproduction. Nematodes became infected after attachment of apical cystospore buds to the nematode cuticle. Apical buds were packed with vesicles with dense fibrillar contents, which were absent from the thallus. Some thalli developed into sporangia while others became paired gametangial cells. Zoospore cleavage was often intrasporangial, although during the early stages of an epidemic partially differentiated zoospores usually were released via an exit tube into a fine vesicle. Packets of tripartite tubular hairs (TTH) were not observed in the cytoplasm of either developing or mature sporangia. TEM of sectioned material and whole mounts of zoospores revealed biflagellate zoospores, some without hairs and others with a proximal row of very short hairs on the anterior flagellum. Gametangial contact was via a short, walled fertilization tube and surplus antheridial and oogonial nuclei remained in their respective gametangial cells until disintegration of the periplasm. The mature oospores had a scalloped, electron opaque, epispore wall layer. These observations will be discussed in relation to the likely phylogenetic position of the Myzocytiopsidales within the oomycetes.

Animals↗
PubMed1997

[Comparative study of genetic adaptation of the Caucasian highlanders to historic and to the new urban environments].

Marriage structure and female reproductive characteristics in a highland isolate and an urban population from Dagestan were compared. The studied urban population could be divided into three groups according to ethnic, genetic, and demographic parameters. In the native, highland population, a steady selection occurred due to a high, uncontrolled birthrate and a high prereproductive mortality. The genetic structure of the urban population still remained at the stage of formation. Different ethnic groups of the female urban population differed both in the rate and directions of selection. The migration of highlanders to the city mainly affected their mortality and morbidity, but not fecundity. The subpopulation of migrants from the highlands who retained a traditional endogamous and inbred marriage structure exhibited a high infant mortality comparable to that in the highland population. The migrant subpopulation in which interpopulation and interethnic marriages were contracted exhibited an increased genetic load expressed as high pre- and perinatal mortalities. The results obtained are discussed in terms of the hypotheses on the adaptive gene complex and the genetic and physiological mechanisms of differential adaptation of highland isolates to environmental changes due to migration or environmental pollution.

Adaptation, Physiological↗
PubMed2000

Multicentric genetic study of Candida albicans isolates from non-neutropenic patients using MLEE typing: population structure and mode of reproduction.

A mycological survey was conducted on non-neutropenic patients in three distinct intensive care units in two hospitals in Marseille (France) from November 1993 to November 1995. Candida albicans positive cultures from 62 patients were included in this study. Every first isolate of each patient was typed by multilocus enzyme electrophoresis (MLEE). The enzyme profiles obtained from 15 polymorphic loci were then compared. This analysis demonstrated a strong population differentiation of C. albicans infective strains within and between the different care units and confirmed the probable preponderant clonal mode of reproduction of this yeast.

Alleles↗
PubMed2001

Distribution of porcine reproductive and respiratory syndrome virus in stillborn and liveborn piglets from experimentally infected sows.

Four pregnant sows were infected 3 weeks before their expected farrowing date with a Korean isolate (North American genotype) of porcine reproductive and respiratory syndrome virus (PRRSV). The distribution of virus in their stillborn and liveborn (killed 7 days after birth) offspring was assessed immunohistochemically and by in-situ hybridization. PRRSV antigen and nucleic acid were detected in lung, thymus, liver, tonsil, spleen, heart, kidney and lymph nodes from both stillborn and liveborn piglets. Positive cells typically exhibited a red (immunohistochemistry) or dark brown (in-situ hybridization) reaction product in the cytoplasm, without background staining. The most consistent labelling for PRRSV was in the thymus, tonsil and lymph nodes. The experiment suggested that, in prenatal piglets, PRRSV replicates primarily in lymphoid tissues, having gained access to them from the placenta via the bloodstream.

Animals↗
PubMed1997

Transcriptional and post-transcriptional regulation of prolactin during the turkey reproductive cycle.

The present study examined turkey prolactin (PRL) transcription and PRL mRNA stability during different reproductive stages. Nuclear run-on transcription assays were performed using isolated nuclei from pituitaries of turkeys at different reproductive stages. Meanwhile, cytoplasmic PRL mRNA and plasma PRL were measured by slot blot and RIA respectively. The PRL transcription, pituitary cytoplasmic PRL mRNA abundance and plasma PRL levels increased after photostimulation and peaked at the incubating stage (P < 0.05). A decrease in PRL transcription, pituitary cytoplasmic PRL mRNA and plasma PRL (P < 0.05) was observed during the transition from incubation to photorefractoriness. Nest-deprivation reduced circulating PRL (P < 0.05), whereas pituitary cytoplasmic PRL mRNA and PRL transcription were not significantly altered from those in incubating birds (P > 0.05). The half-life of PRL mRNA was determined in pituitaries of non-photostimulated, laying, incubating and photorefractory hens. Primary pituitary cell cultures were treated with the transcription inhibitor actinomycin-D and the decay of the pre-existing PRL mRNA was quantified using Northern blot analysis. The PRL mRNA half-life was 1.5- and 1.4-fold greater in incubating and laying birds respectively than in non-photostimulated turkeys (P < 0.05). The half-life of PRL mRNA in photorefractory and incubating hens was similar in spite of great differences in pituitary PRL mRNA steady-state levels and PRL transcription. Our data suggest that photoinduced changes in pituitary PRL mRNA and plasma PRL are due to changes in both PRL transcription and PRL mRNA stability. Nest-deprivation inhibits the PRL releasing mechanism(s) independently of PRL transcription in turkeys.

Animals↗
PubMed1997

Chlamydia psittaci infection in sheep: a paradigm for human reproductive tract infection.

Chlamydiae are important reproductive tract pathogens in a wide variety of animals. In humans, chronic or repeated infection of the female genital tract with Chlamydia trachomatis has been identified as a significant factor in the development of occlusive infertility or increased risk of ectopic pregnancy. The spectrum of reproductive disease recognized in sheep to be caused by Chlamydia psittaci has been primarily restricted to pregnant animals because the organism was clearly identified as a major cause of infectious abortion. However, following pregnancy failure, a chronic chlamydial infection can become established in the reproductive tracts of experimentally infected ewes. Persistent infection of the ewe's reproductive tract may eventually result in pathology, similar to that observed in women infected with C. trachomatis, thus decreasing the breeding life of affected ewes. Furthermore, ewes that experienced C. psittaci induced abortion provide a unique opportunity to study the host: parasite dynamic as it relates to persistent infection. This natural model of persistent infection may, in some ways, be superior to more contrived models in which the chlamydial isolate is not a normal reproductive pathogen of the study animal. Thus, the study of persistent chlamydial infection in sheep may be used for the benefit of both human and veterinary medicine.

Abortion, Veterinary↗
PubMedDate not supplied

[The spatial relationships and social structure of gerbils in the genus Meriones (Gerbillinae, Rodentia)].

Comparative analysis of spatial relations of 4 gerbil species (M. tamariscinus M. meridianus, M. libycus, M. unguiculatus) shows differences in the system of space use between species and within a species--between individuals of different sex. During reproduction period females are inclined to isolation, small overlap of home ranges and high degree of individualisation. Males occupy large home ranges overlapping with territories of several reproductive females. The territories occupied by the males of midday and tamarisk gerbils do not have clear boundaries and the level of their individualization is quite low. The males of Mongolian gerbil (M. unguiculatus) occupy well defined territories with high level of individualization. Spatial relations of M. libycus males are intermediate. The relationships of the males of three investigated species (M. meridianus, M. libycus, M. tamariscinus) being characterised by the high degree of asymmetry of pair connections, are organised according to the principle of agonistic dominance. Relationships between individuals of different family groups of Mongolian gerbils are based on the locus-dependent dominance, while within one family group-on principle of hierarchical subordination. The meaning of specific peculiarities in use of space and dominance relations are discussed in terms of reproductive strategies.

Aging↗
PubMedDate not supplied

Murine female reproductive tract intraepithelial lymphocytes display selection characteristics distinct from both peripheral and other mucosal T cells.

Despite immense effort, the development of vaccines effective at mucosal sites has proceeded at a faltering pace. Efforts concentrating on humoral immunity but neglecting cellular immunity may be misdirected by ignoring many viral mucosal pathogens. Improved understanding of the development and maintenance of lymphocytes populating the reproductive tract (rtIELs) may inform advances in vaccination strategies for sexually transmitted diseases. Recent studies highlight tissue-specific differences in the development of mucosal immunity and suggest that the local milieu may play a role in selection, maintenance and function of resident lymphocytes. Here, we describe MHC class I and thymus dependence of subpopulations of rtIELs. TCRalphabeta+ CD8alphabeta+ T cells in the periphery, intestine, and female reproductive tract are all developmentally dependent on classical class I MHC and the thymus. TCRalphabeta+ CD8alphaalpha+ are absent from the periphery and the rtIELs, but are present and classical MHC class I-independent, in the intestine. In contrast to intestinal TCRgammadelta+ cells, TCRgammadelta+ rtIELs are CD8 negative and thymus dependent. In contrast to peripheral TCRgammadelta+ cells, murine TCRgammadelta+ rtIELs express not a diverse array of Vdelta genes, but rather, a canonical Vdelta1. In summary, lymphocytes isolated from the murine female reproductive tract have characteristics distinct from both peripheral T cells and those found at other mucosal sites. Therefore, for the purpose of vaccination strategies, the female reproductive tract should be regarded neither as peripheral nor mucosal, but rather as a tissue with distinctive immunological characteristics.

Animals↗
PubMed1997

Comparison of four RNA extraction methods for the detection of porcine reproductive and respiratory syndrome virus by RT-PCR.

We compared four commercial RNA isolation methods for the extraction of RNA from porcine reproductive and respiratory syndrome virus (PRRSV). The sensitivity of the methods was determined by extraction of RNA from serial 10-fold dilutions of PRRSV diluted in PRRSV-negative porcine serum or in Eagle's minimal essential medium (EMEM) followed by amplification of extracted nucleic acids by RT-PCR. The PCR products were detected in ethidium bromide-stained agarose gels. The QIAamp viral kit, which is based on binding of RNA to silica particles, was the most sensitive, allowing the detection of an equivalent of 10 TCID50 of virus in 100 microliters of serum or EMEM. The QIAamp-tissue and the TRIzol LS kits detected 100 TCID50 per 100 microliters in both diluents whereas Ultraspec-3 detected 100 TCID50 of virus in EMEM and 1000 TCID50 in serum. These results indicate that QIAamp viral kit has a higher sensitivity for RT-PCR analysis of PRRSV.

Animals↗
PubMed2001

Sea bass Dicentrarchus labrax nervous necrosis virus isolates with distinct pathogenicity to sea bass larvae.

Reproduction of nodavirus disease was performed by experimental infection of sea bass eggs during fertilization or at larval stage 4 with 2 genetically distinguishable nodavirus strains (Sb1 and Sb2) isolated from sea bass collected along the Atlantic and Mediterranean French coast. The pathogenicity of the virus strains was assigned after detection of the virus by ELISA and immunohistochemistry (IHC). The Atlantic (Sb1) strain was more pathogenic than the Mediterranean (Sb2) strain during the fertilization step whilst both strains were pathogenic following experimental exposure of 4 d old larvae. Virus lesions developed in the brain 4 to 6 d following experimental exposure. Experimental ELISA proved very sensitive for detecting the nodavirus in Sb1 or Sb2 experimentally infected larvae, as well as in naturally infected sea bass larvae collected in French hatcheries or in barramundi larvae reared in the Pacific area. The development of an ELISA specific for the 2 nodavirus strains isolated from the sea bass should be useful for the detection of the virus, in addition to other techniques recommended by the Office International des Epizooties (OIE).

Animals↗
PubMed1997

Detection of Mycoplasma pulmonis in cilia-associated respiratory bacillus isolates and in respiratory tracts of rats by nested PCR.

To improve the detection of Mycoplasma pulmonis contamination of isolates of cilia-associated respiratory (CAR) bacillus, we developed a nested PCR method using primers for 16S rRNA gene sequences. Of 140 samples of 16 different CAR bacillus isolates, 73 (52%) were inhibitory in the first PCR, as indicated by the absence of amplicons of the internal control, but only 11 of 140 (7.9%) were inhibitory in the second PCR. Of 27 samples known to contain M. pulmonis, only 12 (44%) were positive in the first PCR, but 25 of 27 (93%) were positive in the second PCR. Nested PCR also detected M. pulmonis in 21 of 61 (34%) CAR bacillus samples from which M. pulmonis could not be cultured and identified 2 additional M. pulmonis-contaminated CAR bacillus isolates. Of 359 respiratory and reproductive tract lavage samples from rats and mice, 35 (9.8%) were inhibitory in the first PCR, but only 15 (4.2%) were inhibitory in the second PCR. Of 72 lavage specimens from rats inoculated with an avirulent, poorly infective M. pulmonis strain, 14 (19%) were positive by nested PCR, but only 2 of 72 (2.8%) were positive by culture. Nested PCR also detected M. pulmonis in 14 of 20 (70%) paraffin sections of lung and trachea from rats and mice inoculated with CAR bacillus isolates known to contain M. pulmonis, whereas single PCR gave no positive results. We conclude that nested PCR is superior to single PCR or culture for detecting M. pulmonis, and that M. pulmonis is present in all but four CAR bacillus isolates in our collection that were from naturally infected rats; the four isolates that were exceptions were obtained from rats from a single colony.

Animals↗
PubMed2006

Isolation of 151 mutants that have developmental defects from T-DNA tagging.

In order to understand the mechanisms underlying plant development, a necessary first step involves the elucidation of the functions of the genes, via the analysis of mutants that exhibit developmental defects. In this study, an activation tagging mutant library harboring 80,650 independent Arabidopsis transformants was generated in order to screen for developmental mutants. A total of 129 mutants manifesting dominant developmental abnormalities were isolated, and their T-DNA insertion loci were mapped. The activation of one or more genes adjacent to a T-DNA insertion locus was confirmed in eight dominant mutants. A gene adjacent to the right border was usually activated by the 35S enhancers. Interestingly, the transcriptional activation of multiple genes within a broad range was observed in one of the mutants, which raises the possibility that activation by the 35S enhancers was not limited strictly to a single gene. In order to gain a better understanding of sexual reproduction in higher plants, we isolated 22 mutants exhibiting defects in female gametophyte development, and determined their T-DNA insertion loci. We propose that this mutant population may prove useful in the further determination of the functions of genes that play important roles in plant development.

Base Sequence↗
PubMed2001

The effect of isolation on the life-history traits of Pseudosuccinea columella (Pulmonata: Lymnaeidae).

A population of Pseudosuccinea columella was raised under laboratory conditions and its life tables were determined in isolated and paired snails. Isolated snails were significantly larger in shell size than paired snails from five weeks of age onward. Also, statistically significant differences were found for the number of eggs per mass per individual from week 5 to 9, isolated snails exhibiting the highest values. The intrinsic and finite rates of increase were greater in isolated than in paired snails. Either an inhibition of the reproductive output between individuals or the advantage of selfing may be the cause of the differences in this species, acting as a possible mechanism that increase the fitness of isolated snails.

Animals↗
PubMed1987

Angiostrongylus cantonensis: immunoblot analysis of the antigens recognized by rats.

Following infection of rats with Angiostrongylus cantonensis, occurrence of anti-parasite antibody in the serum was determined with special reference to the antigens recognized by host IgG antibodies, using SDS-PAGE combined with an immunoblotting technique. Three saline extracts of digestive organ, reproductive organ and body wall, isolated from adult female A. cantonensis, were used as crude antigenic solutions. Then 7 to 49 days after infection, IgG antibodies directed predominantly against a single antigen, referred to as Ac-1 antigen, were detected. After 91 days or more, infected rats formed antibodies not only against the Ac-1 antigen, but also against a wide variety of other components with molecular weights in the range of 26,000-220,000 dalton. By using an antiserum against Ac-1 antigen as a probe, it was shown that the molecular weight and subunit structure, as well as the immunoelectrophoretic mobility, varied according to the organ from which the antigenic extract was prepared. The Ac-1 protein in the extract of the reproductive organ, one of the major sources of the Ac-1 antigen, showed the same electrophoretic mobility as alpha-globulin. It has a molecular weight in the range of 100,000-200,000 dalton under both non-reducing and reducing conditions. Immunohistochemical studies, using the same antiserum and sectioned adult female worms, found Ac-1 antigen in the cytoplasm of oocytes at different stages of development, and in the lateral cord.

Angiostrongylus↗
PubMed2003

Isolation and characterization of a maintenance DNA-methyltransferase gene from peach (Prunus persica [L.] Batsch): transcript localization in vegetative and reproductive meristems of triple buds.

A cDNA coding for a DNA (cytosine-5)-methyltransferase (METase) was isolated from peach (Prunus persica [L.] Batsch) and the corresponding gene designated as PpMETI. The latter encoded a predicted polypeptide of 1564 amino acid residues and harboured all the functional domains conserved in the maintenance METases group type I. PpMETI was a single copy in the cultivar Chiripa which was used as a model in the present study. Expression analyses revealed that PpMETI transcripts were more abundant in tissues with actively proliferating cells such as apical tips, uncurled leaves, elongating herbaceous stems, and small immature fruits. Peach plants bear bud clusters (triads or triple buds), consisting of two lateral and one central bud with floral and vegetative fates, respectively. PpMETI in situ hybridization was performed in triple buds during their entire developmental cycle. High and low levels of PpMETI transcript were related to burst and quiescence of vegetative growth, respectively. Message localization distinguished lateral from central buds during the meristem switch to the floral phase. In fact, the PpMETI message was abundant in the L1 layer of protruding domes, a morphological trait marking the beginning of floral transition. The PpMETI transcript was also monitored during organ flower formation. Altogether, these data suggest a relationship between DNA replication and PpMETI gene expression.

Animals↗
PubMed1994

Experimental reproduction of bovine fetal Neospora infection and death with a bovine Neospora isolate.

Studies were conducted to determine the pathogenic potential of the recently isolated bovine Neospora protozoa (BPA-1) for the bovine fetus. Cows chosen for study had Neospora titers < 160 using an indirect immunofluorescent antibody (IFA) test. Four experimental groups were studied. In group 1, 2 fetuses were inoculated in utero at 118 days gestation with culture-derived Neospora tachyzoites. A pregnant control cow was housed in the same pen, observed daily and screened serologically for evidence of exposure to Neospora. In group 2, 2 cows were infected with Neospora tachyzoites at 138 or 161 days gestation, and 1 control cow was given uninfected cell culture suspension simultaneously at 154 days gestation. Groups 3 (85 days gestation) and 4 (120 days gestation) each consisted of 2 cows infected with Neospora tachyzoites and 1 control cow given uninfected material at the same stage of gestation. Dead fetuses were surgically removed from the infected cows in group 1 on postinfection day (PID) 17. The histopathology was compatible with protozoal fetal infection, and protozoa were identified by immunohistochemistry. Viable fetuses were removed surgically from cows in group 2 on PID 28-30. The histopathology was compatible with protozoal fetal infection, protozoa were identified by immunoperoxidase techniques, and Neospora tachyzoites were reisolated in vitro from tissues of the 2 infected fetuses. In groups 3 and 4, the control fetus and 1 infected fetus were removed surgically between PID 26 and PID 33. The remaining infected cows were observed until fetal death or abortion occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

Abortion, Veterinary↗