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J M Morrell

Publications and source records attributed to J M Morrell.

29 records · Page 2Linked to original sources
PubMed1991

Applications of flow cytometry to artificial insemination: a review.

Flow cytometry is a technique in which sub-populations of cells can be analysed and separated according to the staining pattern seen with various fluorescent markers. This review describes some of the ways in which flow cytometry can be applied to the investigation of sperm populations, either as a means of quality control of semen or to examine the characteristics of different sub-populations of sperm within an ejaculate. These methods can replace or augment existing subjective assessments of semen characteristics. Using this technique it is possible to produce aliquots of sexed sperm for insemination or for in vitro fertilisation. An objective assessment can be made of the effects of environmental stress on male physiology by monitoring changes in semen quality.

Animals↗
PubMed1991

Apparent decline in fertility in heifers after repeated oestrus synchronisation with cloprostenol.

Over several years groups of heifers which were repeatedly treated with the PGF2 alpha analogue, cloprostenol, to synchronise oestrus were artificially inseminated. When sperm treatment was optimised, a reduction in conception rate was observed which was related to the number of synchronisation treatments the animals had received. Although factors such as a seasonal reduction in fertility may have contributed to the effect, there appeared to be a decrease in the proportion of animals becoming pregnant after successive synchronisations. Possible explanations for this observation are suggested.

Animals↗
PubMed1991

Pyroglutamylglutamylprolineamide is present in rat anterior and posterior pituitary gland.

A new TRH-like peptide pyroglutamylglutamylprolineamide (pGlu-Glu-ProNH2) has recently been purified and characterized from both the rabbit prostate complex and human semen. In this study, TRH-immunoreactive peptides were extracted from anterior pituitary, posterior pituitary and hypothalamus and subjected to gel exclusion chromatography. For each tissue, TRH was resolved from pGlu-Glu-ProNH2 by anion-exchange chromatography at pH 7.6. In the anterior pituitary, 63% of the TRH immunoreactivity was chromatographically identical to pGlu-Glu-ProNH2 whereas in the posterior pituitary the new peptide represented less than 5% of the total TRH immunoreactivity. Only trace levels of pGlu-Glu-ProNH2 were observed in hypothalamus, suggesting that the acidic TRH-related peptide found in the anterior pituitary may not be of hypothalamic origin. The new TRH-like peptide was purified from whole pituitaries by gel exclusion and ion-exchange chromatography, followed by high power liguid chromatography and was shown to have chromatographic properties identical to pGlu-Glu-ProNH2. Amino acid analysis of the purified peptide revealed glutamic acid and proline residues in the ratio Glx:2 Pro:1, which is the expected composition of pGlu-Glu-ProNH2 after acid hydrolysis.

Animals↗
PubMed1990

Use of an ELISA for plasma progesterone to facilitate rabbit husbandry.

There is a need for a simple and accurate method for detecting pregnancy in rabbits; the available methods are not ideal and may not provide the diagnosis at an appropriate time for the early remating of non-pregnant animals. This paper describes the use of an ELISA kit to measure progesterone concentrations in rabbit plasma; a qualitative assessment of the results appears to be sufficiently accurate for pregnancy diagnosis, as does the use of serum instead of plasma. The technique can be used to predict ovulation and to distinguish between pregnant and pseudopregnant animals.

Animal Husbandry↗
PubMed1989

The TRH-related peptide pyroglutamyglutamylprolinamide is present in human semen.

We have recently identified a novel peptide in the rabbit prostate complex which cross-reacts with an antibody to thyrotrophin-releasing hormone (TRH) and has the structure pGlu-Glu-ProNH2. In the present study, high concentrations of a TRH-related tripeptide and also a polypeptide (10-12 kDa) containing a TRH-immunoreactive peptide at its C-terminus were detected in human semen. The low molecular mass TRH-like peptide and the immunoreactive fragment from the polypeptide were isolated from human semen and shown to have identical structures. Amino acid analysis suggested compositions Glx2, Pro1, and after mild acid hydrolysis, the same sequence, Glu-Glu-Pro, was established for the two peptides. Fast atom bombardment (FAB) mass spectrometry yielded a pseudomolecular ion (M + H)+ of 355.38 which was identical to that of the synthetic peptide pGlu-Glu-ProNH2. The data demonstrate that human semen contains the TRH-like peptide pyroglutamylglutamylprolinamide and also a polypeptide terminating in the sequence Gln-Glu-ProNH2.

Adult↗
PubMed1989

Offspring from inseminations with mammalian sperm stained with Hoechst 33342, either with or without flow cytometry.

The technique of vital staining with a fluorochrome and subsequent flow cytometry has been employed to investigate the DNA content of living sperm. There have been several reports of chromosomal damage caused by staining cells with a bis-benzimidazole dye. Hoechst 33342, either with or without subsequent flow cytometry. Therefore the use of this technique might be expected to affect adversely the fertilising capacity of inseminated sperm, or to result in the production of congenital deformities in the young. Insemination experiments to date have resulted in the production of more than 400 offspring in four species, including 5 successive generations of rabbits, where stained or sorted sperm were used. All progeny were observed to be normal by anatomical criteria. There was no evidence to suggest that sperm treated in this manner were unable to fertilise oocytes in vivo or that embryonic development was affected.

Animals↗
PubMed1989

Thyrotrophin-releasing hormone-related polypeptides in rabbit prostate and semen are different from those in rabbit hypothalamus.

TRH-related peptides were extracted from the hypothalamus and prostate gland of the rabbit. The peptides were fractionated by gel exclusion chromatography and located by trypsin digestion and radioimmunoassay with antibodies to TRH amide and TRH-Gly Lys. In the hypothalamus TRH-related peptides containing approximately 16 and 30 residues were observed: in these peptides the extensions to the TRH sequence were exclusively in the C-terminal direction. In addition, the three-residue form of TRH was also present. In the prostate complex, the predominant TRH-related peptide contained approximately 50 residues and the extension to the TRH tripeptide was on the N-terminal side; a three-residue form of immunoreactive TRH was also demonstrated. The same pattern of TRH-related peptides was shown to be present in rabbit semen. The results reveal the existence of a novel TRH-related polypeptide in the prostate and semen which does not occur in the hypothalamus. This peptide appears to undergo secretion.

Animals↗
PubMed1988

Sexing of sperm by flow cytometry.

Economics dictate that livestock producers will be under increasing pressure to optimise output. A technique for sex pre-selection could help by reducing the number of females required to produce a given number of progeny of the desired sex; the technique would be particularly useful to the dairy industry. Live mammalian sperm, stained with a vital dye and analysed by flow cytometry, show a bimodal fluorescence distribution. Such bimodality may represent two overlapping subpopulations of X- and Y-chromosome bearing sperm. To test this hypothesis, sperm from the two subpopulations were separated using the sorting capacity of a flow cytometer and were used for the insemination of suitably prepared females. The sex of the resulting progeny was determined either by anatomical criteria or by identification of the sex chromosomes by karyotyping. Insufficient data are available so far to provide statistically significant evidence in support of the hypothesis, but a preliminary sequential analysis indicates a progressive tendency towards significance.

Animals↗
PubMedDate not supplied

Artificial insemination in rabbits.

Artificial insemination (AI) in rabbits can be a useful aid to colony management. In this review, simple non-invasive techniques for semen collection and AI are described. Conception rates following AI can be equivalent to, or better than, those achieved by natural mating, with the added advantage that contact between animals is avoided. Ovulation can be induced reliably by the administration of a gonadotrophin releasing hormone analogue, buserelin, as an alternative to the use of a vasectomized buck or the injection of luteinizing hormone. The use of enzyme-linked immunoassay kits for progesterone assay can assist colony management by rapidly identifying non-pregnant animals for re-insemination. Frozen-thawed sperm have been inseminated but careful attention to the cryopreservation technique is required to ensure good conception rates.

Animals↗
PubMedDate not supplied

Influence of semen collection method on ejaculate characteristics in the common marmoset, Callithrix jacchus.

A source of normal spermatozoa (sperm) is required for many andrological and reproductive studies. Ideally the method used for semen collection should be repeatable and reliable but should not influence sperm characteristics or sperm function. Two methods of semen collection from marmosets, vaginal washing after copulation and electroejaculation, were compared in terms of the success rate in obtaining samples and the characteristics of the sperm suspensions. Vaginal washing was shown to be a reliable, repeatable, and apparently non-stressful method of obtaining ejaculates, with 8 out of 10 males ejaculating on at least four of the five attempts. The semen was of good quality as assessed by conventional means, and the sperm were highly fertile when used for artificial insemination (Al; 100% conception rate). In contrast, fewer ejaculates were obtained from the same males by electroejaculation (success rate 30%), sperm survival in vitro was reduced compared to sperm collected by vaginal washing (0.93 +/- 0.15 days for electroejaculated sperm compared to 1.98 +/- 0.3 days for sperm from vaginal washing), and the number of animals giving birth after Al was smaller (0 vs. 6; P < 0.05). The proportions of motile (74.8 vs. 70.7%), live (84.7 vs. 81%), and morphologically normal (91.9 vs. 87.6%) sperm in the ejaculates were not affected by the semen collection method, but velocity parameters, such as curvilinear velocity, straight line velocity, and average path velocity, as assessed by computerized motility analysis, were significantly lower in vaginal washings than in electroejaculates (P < 0.023, 0.008, and 0.008, respectively). Mean angular deviation and beat cross frequency were greater in vaginal washings than in electroejaculates (P < 0.016 and 0.008, respectively). Therefore the effect of semen collection method on sperm function should always be considered when designing reproductive studies.

Animals↗