Biomedical subjects

C M Austin

Publications and source records attributed to C M Austin.

18 recordsLinked to original sources

PubMed2006

The complete mitochondrial genome of the mantid shrimp Harpiosquilla harpax, and a phylogenetic investigation of the Decapoda using mitochondrial sequences.

The complete mitochondrial DNA sequence was determined for the mantid shrimp Harpiosquilla harpax. These data demonstrate that the H. harpax mitochondrial genome is a 15,714 bp circular molecule and encodes the typical 37 metazoan mitochondrial genes (13 protein-coding, 22 tRNA, and two rRNA genes). The gene arrangement of H. harpax is consistent with that of the putative arthropod ancestral gene order as depicted by Limulus polyphemus. H. harpax was employed as an outgroup taxon for a phylogenetic investigation of the Decapoda using sequences from complete mitochondrial genomes. Whilst our results are largely in agreement with current taxonomic treatments, the relationships indicated among the reptantian decapods are novel. Our results provide strong statistical support for a sister-group relationship between the Achelata and the Astacida. These findings not only refute previous phylogenetic hypotheses, but also have serious implications for the interpretation of morphological and developmental evolution in the Decapoda. In addition we also investigated the effects of outgroup selection on the resolution of ingroup relationships. We found outgroup choice to significantly influence tree topology thus reinforcing the importance of appropriate outgroup selection in phylogenetic studies.

Animals↗

PubMed2006

A microsatellite linkage map of the blacklip abalone, Haliotis rubra.

There is considerable scope for genetic improvement of cultured blacklip abalone Haliotis rubra in Australia using molecular marker-assisted, selective-breeding practices. Such improvement is dependent on the availability of primary genetic resources, such as a genetic linkage map. This study presents a first-generation linkage map of H. rubra, containing 122 microsatellite markers typed in a single full-sib family. These loci mapped to 17 and 20 linkage groups for the male and female respectively, and when aligned, the consensus map represented 18 linkage groups. The male linkage map contained 102 markers (one unlinked) covering 621 cM with an average intermarker spacing of 7.3 cM, and the female map contained 98 markers (eight unlinked) covering 766 cM with an average intermarker spacing of 9.8 cM. Analysis of markers informative in both parents showed a significantly higher recombination rate in the female parent, with an average male-to-female recombination ratio of 1:1.45 between linked pairs of markers. This linkage map represents a significant advancement in the genetic resource available for H. rubra and provides a framework for future quantitative trait loci mapping and eventual implementation of marker-assisted selection.

Animals↗

PubMed2005

Using mitochondrial nucleotide sequences to investigate diversity and genealogical relationships within common carp (Cyprinus carpio L.).

Direct sequencing of mitochondrial DNA (mtDNA) D-loop (745 bp) and MTATPase6/MTATPase8 (857 bp) regions was used to investigate genetic variation within common carp and develop a global genealogy of common carp strains. The D-loop region was more variable than the MTATPase6/MTATPase8 region, but given the wide distribution of carp the overall levels of sequence divergence were low. Levels of haplotype diversity varied widely among countries with Chinese, Indonesian and Vietnamese carp showing the greatest diversity whereas Japanese Koi and European carp had undetectable nucleotide variation. A genealogical analysis supports a close relationship between Vietnamese, Koi and Chinese Color carp strains and to a lesser extent, European carp. Chinese and Indonesian carp strains were the most divergent, and their relationships do not support the evolution of independent Asian and European lineages and current taxonomic treatments.

Animals↗

PubMed2002

Amplification of multiple copies of mitochondrial Cytochrome b gene fragments in the Australian freshwater crayfish, Cherax destructor Clark (Parastacidae: Decapoda).

Non-coding copies of fragments of the mitochondrial genome translocated to the nucleus or pseudogenes are being found with increasing frequency in a diversity of organisms. As part of a study to evaluate the utility of a range of mitochondrial gene regions for population genetic and systematic studies of the Australian freshwater crayfish, Cherax destructor (the yabby), we report the first detection of Cytochrome b (Cyt b) pseudogenes in crustaceans. We amplified and sequenced fragments of the mitochondrial Cyt b gene from 14 individuals of C. destructor using polymerase chain reaction (PCR) with primers designed from conserved regions of Penaeus monodon and Drosophila melanogaster mitochondrial genomes. The phylogenetic tree produced from the amplified fragments using these primers showed a very different topology to the trees obtained from sequences from three other mitochondrial genes, suggesting one or more nuclear pseudogenes have been amplified. Supporting this conclusion, two highly divergent sequences were isolated from each of two single individuals, and a 2 base pair (bp) deletion in one sequence was observed. There was no evidence to support inadvertent amplification of parasite DNA or contamination of samples from other sources. These results add to other recent observations of pseudogenes suggesting the frequent transfer of mitochondrial DNA (mtDNA) genes to the nucleus and reinforces the necessity of great care in interpreting PCR-generated Cyt b sequences used in population or evolutionary studies in freshwater crayfish and crustaceans more generally.

Animals↗

PubMed2001

Catecholamine release and uptake in the mouse prefrontal cortex.

Monitoring the release and uptake of catecholamines from terminals in weakly innervated brain regions is an important step in understanding their importance in normal brain function. To that end, we have labeled brain slices from transgenic mice that synthesize placental alkaline phosphatase (PLAP) on neurons containing tyrosine hydroxylase with antibody-fluorochrome conjugate, PLAP-Cy5. Excitation of the fluorochrome enables catecholamine neurons to be visualized in living tissue. Immunohistochemical fluorescence with antibodies to tyrosine hydroxylase and dopamine beta-hydroxylase revealed that the PLAP labeling was specific to catecholamine neurons. In the prefrontal cortex (PFC), immunohistochemical fluorescence of the PLAP along with staining for dopamine transporter (DAT) and norepinephrine transporter (NET) revealed that all three exhibit remarkable spatial overlap. Fluorescence from the PLAP antibody was used to position carbon-fiber microelectrodes adjacent to catecholamine neurons in the PFC. Following incubation with L-DOPA, catecholamine release and subsequent uptake was measured and the effect of uptake inhibitors examined. Release and uptake in NET and DAT knockout mice were also monitored. Uptake rates in the cingulate and prelimbic cortex are so slow that catecholamines can exist in the extracellular fluid for sufficient time to travel approximately 100 microm. The results support heterologous uptake of catecholamines and volume transmission in the PFC of mice.

Alkaline Phosphatase↗

PubMed2000

Is infant-directed speech prosody a result of the vocal expression of emotion?

Many studies have found that infant-directed (ID) speech has higher pitch, has more exaggerated pitch contours, has a larger pitch range, has a slower tempo, and is more rhythmic than typical adult-directed (AD) speech. We show that the ID speech style reflects free vocal expression of emotion to infants, in comparison with more inhibited expression of emotion in typical AD speech. When AD speech does express emotion, the same acoustic features are used as in ID speech. We recorded ID and AD samples of speech expressing love-comfort, fear, and surprise. The emotions were equally discriminable in the ID and AD samples. Acoustic analyses showed few differences between the ID and AD samples, but robust differences across the emotions. We conclude that ID prosody itself is not special. What is special is the widespread expression of emotion to infants in comparison with the more inhibited expression of emotion in typical adult interactions.

Adult↗

PubMed1996

Limiting multiple pregnancy in in vitro fertilization/embryo transfer (IVF-ET) cycles.

PURPOSE: Our purpose was to assess how the number of embryos transferred can be adjusted to limit multiple gestations. METHODS: A retrospective analysis of 535 consecutive embryo transfers for the years 1991-1993 was conducted. RESULTS: Fewer than three embryos were associated with a low pregnancy rate. Pregnancy rates were highest in women less than 35 when four or more embryos were transferred. With four or more embryos, multiple gestation pregnancy correlated with the number of high-quality embryos transferred. The risk of triplets and quadruplets was greatest for women less than 40. CONCLUSIONS: Multiple-embryo transfer carries a risk of plural gestation. The risk of multiple pregnancy cannot be eliminated without decreasing the pregnancy rate. The risk of high-order multiple pregnancy was best correlated with the number of good-quality embryos transferred. While all are at risk, patients younger than 40 were at highest risk.

Adult↗

PubMed1996

Clinical experience with synthetic serum substitute as a protein supplement in IVF culture media: a retrospective study.

OBJECTIVE: Our objective was to evaluate the efficacy of Synthetic Serum Substitute (Irvine Scientific--Materials Section, Santa Ana, CA), a globulin-enriched protein preparation containing human serum albumin for supplementation of IVF culture media. DESIGN: We retrospectively analyzed IVF cycles performed at MacDonald Womens Hospital between January 1992 and November 1994. IVF cycles were reviewed and classified according to the nature of protein supplementation used in the embryo culture medium. Three protein supplements utilized during this time period were compared: Synthetic Serum Substitute (SSS), Plasmanate (PL), and maternal serum (MS). RESULTS: Although clinical pregnancy rates among the three treatment groups were not statistically different, there was a definite trend toward a higher pregnancy rate with SSS supplementation (SSS, 38.2%; MS, 28.0%; and PL, 24.9%). Embryos grown in SSS-supplemented culture media had a significantly higher implantation rate (17.8 vs 10.4 and 10.3%, respectively, for MS and PL). Preliminary data also suggest that human embryo development and blastulation in vitro were enhanced by this protein supplement. CONCLUSIONS: The higher implantation rate with SSS suggests that it may be superior to both maternal serum and Plasmanate in supporting human embryo development in vitro. Whether blastocysts derived from PL- and SSS-supplemented media are able to implant and give rise to clinical pregnancies remains to be seen.

Adult↗

PubMed1995

Cornual heterotopic pregnancy and cornual resection after in vitro fertilization/embryo transfer. A report of two cases.

BACKGROUND: Heterotopic pregnancy occurs in about 1% of pregnancies achieved with assisted reproductive technologies. The incidence of cornual pregnancy is approximately 1% of all ectopics. CASES: Two patients became pregnant after treatment with IVF-ET. Both presented during the first trimester with evidence of an acute abdomen and ultrasonographic suspicion for cornual heterotopic pregnancies. The diagnoses were confirmed by laparoscopy, and treatment was undertaken with laparotomy with cornual resection. Both delivered viable infants by cesarean section; the first patient delivered a twin gestation at 28 weeks and the second a singleton pregnancy at 37 weeks. All infants were doing well two months after delivery. CONCLUSION: Abnormal pregnancies can be detected after IVF-ET with careful follow-up, transvaginal ultrasound studies, serial hCG measurements and pelvic examinations. Cornual heterotopic pregnancies can be successfully treated with cornual resection, especially in cases presenting during the second trimester or when there is clinical evidence of an acute abdomen. All deliveries should be performed by cesarean section at term prior to labor or when tocolysis for premature labor has failed.

Embryo Transfer↗

PubMed1988

Intermediates in the refolding of ribonuclease at subzero temperatures. 2. Monitoring by inhibitor binding and catalytic activity.

The kinetics of refolding of ribonuclease A were monitored by the return of catalytic activity and inhibitor binding at -15 degrees C in 35% methanol cryosolvent at pH* 3.0 and 6.0. Catalytic activity was measured with cytidine 2',3'-cyclic monophosphate as substrate; inhibitor binding was determined with the competitive inhibitor cytidine 2'-monophosphate. Biphasic kinetics were observed at pH* 3.0 for both return of catalytic activity and inhibitor binding. At pH* 6.0 the rate of return of catalytic activity was monophasic, whereas that of inhibitor binding was biphasic. For both inhibitor binding and catalytic activity one of the observed rates was pH-dependent. Full return of catalytic activity was obtained at the completion of the refolding process. The observations are interpreted in terms of two parallel pathways of refolding for slow-refolding ribonuclease, with several native-like, partially folded intermediate states on the minor slow-refolding pathway. Of particular note is the presence of at least one such species that has inhibitor-binding capacity but not catalytic activity. This may be rationalized in terms of the known native structure. In addition, an intermediate is postulated which has the incorrect Pro-93 conformation and only partial catalytic activity (42% of the native). The slowest observed transient is attributed to the isomerization of this proline residue and return of full catalytic activity.

Binding Sites↗

PubMed1968