Search PubMed⌕ Search

Biomedical subjects

I Maudlin

Publications and source records attributed to I Maudlin.

At least 73 records · Page 4Linked to original sources
PubMed1984

Serum factors and the maturation of Trypanosoma congolense infections in Glossina morsitans.

Removal of certain components from pig or cow blood greatly reduces the maturation rate of Trypanosoma congolense infections in Glossina morsitans fed on such diets. In particular, delipidation of serum has the same effect as complete removal of dietary serum with few midgut infections reaching maturity. The addition of gamma-globulin to red cells partially restores the ability of immature infections to transform suggesting that serum lipids or other serum factors are not acting directly on midgut trypanosome metabolism but indirectly through interactions between dietary constituents and the flies' metabolic processes. As susceptibility to T. congolense infection is known to be maternally inherited in G. morsitans, it is suggested that serum factors act through the flies' symbionts to induce maturation in midgut infections.

Animals↗
PubMed1984

Maintenance of Glossina morsitans morsitans on antiserum to procyclic trypanosomes reduces infection rates with homologous and heterologous Trypanosoma congolense stocks.

Three experimental groups of male Glossina morsitans morsitans were infected at their first feed with procyclic forms of different stocks of Trypanosoma congolense and subsequently maintained on a diet containing rabbit antiserum to one of these stocks. Control flies were similarly infected but were then maintained on normal rabbit serum. Dissection of the flies 19-21 days post infection showed a reduction in both immature and mature infection rates in all groups fed on antiserum by comparison with control flies. These results suggest that vaccination with a single procyclic T. congolense strain could reduce transmission of both homologous and heterologous T. congolense strains which might, in certain epidemiological circumstances, provide an alternative or additional control method for African trypanosomiases.

Animals↗
PubMed1980

Chiasma distribution in mouse oocytes during diakinesis.

The distribution of chiasmata in the mouse was examined by measurement of a single metacentric bivalent in 173 oocytes taken from 36 mice of the Rb3Bnr stock. Frequency distribution analysis revealed a well defined pattern of chiasma formation in both arms of the metacentric and, as in other organisms, interference and localization were thought to be major factors influencing this pattern. Despite the tendency for bivalents to form terminal associations at metaphase in the mouse and reported differences in chiasma frequency between early and late stages of meiosis, analysis of bivalents at diakinesis has produced no quantitative support for the concept of terminalization of chiasmata during meiosis.

Animals↗
PubMed1979

Analysis of aneuploidy in first-cleavage mouse embryos fertilized in vitro and in vivo.

First-cleavage mouse embryos, fertilized in vitro and in vivo, provide ideal material for chromosomal analysis. With the appropriate incubation in a mitotic inhibitor, syngamy is prevented and the sperm- and egg-derived chromosomes remain as separate clusters. Because the latter chromosomes undergo condensation sooner than those from the spermatozoon, the parental source of chromosome sets can be identified even without a marker chromosome. Thus these embryos can be analyzed both for the primary incidence and the parental source of a number of chromosomal anomalies, including aneuploidy. By using fertilization in vitro to obtain the embryos, the synchrony of fertilization and nuclear development is such that 80% or more of the chromosomal preparations are suitable for analysis, compared with about 50% for embryos fertilized in vivo.

Aneuploidy↗
PubMed1979

Incidence of polyspermy in mouse eggs fertilized in vivo and in vitro after administration of progesterone and oestradiol.

Female mice, induced to superovulate, were injected subcutaneously with progesterone or oestradiol near the time when hCG was given. The incidence of polyspermy in first-cleavage embryos following mating or in-vitro fertilization was then determined. There were no detectable differences in the incidence or degree of polyspermy between treated and control in either the in-vitro or in-vivo groups, although the mean incidence of polyspermy was higher in vitro than in vivo. Furthermore, there was no detectable acceleration of egg transport after administration of either hormone.

Animals↗
PubMed1978

The effect of sperm and egg genotype on the incidence of chromosomal anomalies in mouse embryos fertilized in vitro.

Analysis of the chromosomes of 1-cell mouse embryos fertilized in vitro showed that the incidence of polyploidy is independent of both sperm and egg genotype. No significant differences were detected between groups of eggs from 5 strains of mice fertilized by spermatozoa from a single strain, TO, or between groups of (C57BL/10 X CBA) F1 eggs fertilized by spermatozoa from 2 strains, CBA/H-T6 and TO, although there was significant heterogeneity between individual males in the latter set of experiments. While the majority of polyploids were triploids resulting from dispermic fertilization, some derived from diploid spermatozoa were also found.

Aneuploidy↗
PubMed1978

Maternal age and the incidence of aneuploidy in first-cleavage mouse embryos.

Eggs obtained from young virgin and aged parous female mice were fertilized in vitro to compare the incidence of aneuploidy in the resulting first-cleavage embryos. There was a significantly higher incidence of aneuploidy in the aged group (7.5% versus 3.3%) and this was due solely to a higher proportion of trisomic female chromosome complements; there was no difference in the incidence of monosomics. These results thus suggest that non-disjunction occurs more frequently in eggs from older females, leading to the production of aneuploid embryos.

Aneuploidy↗
PubMed1977

The effect of PMSG dose on the incidence of chromosomal anomalies in mouse embryos fertilized in vitro.

Chromosomal analysis of first-cleavage mouse embryos obtained by fertilization of TO eggs with TO spermatozoa in vitro revealed that the incidence of polyploidy was proportional to the dose of PMSG given to the donor females. The dose-response was shown to be linear, with the level of polyploidy rising from 8-0% with a PMSG dose of 1-5 i.u./female to 20-8% with 10-0 i.u./female. A total of 64 polyploid embryos was found among the 452 examined and in all cases the polyploidy was the result of polyspermy or fertilization by diploid spermatozoa.

Aneuploidy↗
PubMed1976

The inheritance of radiation induced semi-sterility in Rhodnius prolixus.

Eggs from crosses of 40 adult male R. prolixus irradiated with 6K rad gamma-rays with normal females had a mean fertility of 23.9%, only 2 crosses being completely sterile. The 86 F1 progeny of both sexes, when outcrossed with normal mates, had a mean egg fertility of 12.6;, and 43 of these matings were completely sterile. Twenty-eight "F2" bugs reared from F1 X normal crosses were mated with normal partners and had a mean fertility of 44.6%, 6 of them being fully fertile, a reversal towards normal fertility. Cytogenetic examination of F1, "F2" and "F3" males showed that these changes in fertility correlated well with the degree of chromosomal abnormality found. The very high recovery rate of translocations in F1 generation males can be related to the holocentric chromosomes of these bugs which precludes the formation of dicentric chromosomes which are inviable in monocentric species. In F1 and "F2" males the majority of one bug was found with a ring of IV chromosome association and it is suggested that chromosome morphology, combined with a low chiasma frequency, favours chain association. Most chain multivalents showed linear orientation which may lead to duplication deficiencies and zygotic death. However, "parellel", "indifferent" and the more stable "convergent" modes of chain orientation were also all observed indicating that survival of some translocations in this species may be possible. The survival to the "F2" generation of chromosomal fragments confirmed the holocentric nature of triatomine chromosomes. It is suggested that semi-sterile males would prove more effective than releases of completely sterile males for reducing wild populations of R. prolixus, because of the delayed effects of sterilizing radiation consequent upon the holocentric structure of triatomine chromosomes.

Animals↗