Australian journal of biological sciences最新文献

{"title":"Current topics in artificial insemination of sheep.","authors":"G Evans","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>There have been developments in several aspects of artificial insemination (AI) in recent years, some of which have been directly responsible for proliferation of AI in the sheep-breeding industries of several countries. The most notable advances have probably been associated with the development of intrauterine insemination by laparoscopy. There is potential for refinement of some of the related techniques, particularly in the area of control of ovulation and definition of appropriate times and optimum doses of spermatozoa for insemination. It is unlikely that laparoscopic AI will be developed sufficiently that it will become readily affordable, and therefore widely practised, by commercial producers. Unfortunately, there has been little progress in the past few years in improvement of the methods of cryopreservation of ram semen. There is considerable potential for AI to have a significant impact on the genetic improvement of sheep, though this has yet to be evaluated in practice. However, if the full potential of AI in sheep is to be realized, it will likely only happen when methods of freezing semen are improved sufficiently that cervical or even vaginal insemination can be widely used with frozen-thawed semen, or when practicable methods of deep cervical or intrauterine insemination through the cervix are developed.</p>","PeriodicalId":8573,"journal":{"name":"Australian journal of biological sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14209414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Embryo manipulation in research and animal production.","authors":"J N Shelton","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Research in developmental biology has resulted in techniques to accelerate changes in gene frequency and to interfere directly in the genome. Procedures already in use or being adapted to livestock include embryo transfer, chimera production, embryo splitting, gene transfer and nuclear transplantation. Experiments with mouse embryos are revealing the principles governing embryonic development and differentiation and illustrate the need for these investigations to be extended to embryos of livestock. The optimal combination of these technologies in animal production strategies will depend upon further research and the role of animal products in society.</p>","PeriodicalId":8573,"journal":{"name":"Australian journal of biological sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14209415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Control of fertility and fecundity of sheep by means of hormonal manipulation.","authors":"R J Scaramuzzi,&nbsp;J A Downing,&nbsp;B K Campbell,&nbsp;Y Cognie","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The results of four experiments are presented in summary form. The data are considered in relationship to the improvement of the fecundity and fertility of the Australian ewe breeding flock. In the first, three commonly used methods of oestrous synchronization were examined and showed differences that are attributed to the different patterns of hormonal changes associated with the methods demonstrated. The second experiment looked at the use of active immunization against testosterone and concluded that this method can improve fecundity but not fertility. The third experiment, a group of five trials, studied the use of progestagen sponges and PMSG in anoestrous ewes as a means of inducing normal fertility. The extensive data produced in this experiment allowed the relationships between ovulation rate and fertility and between fertility and prolificacy (fecundity) to be examined. Fertility appeared greatest when the mean flock ovulation rate was about 2.5. At this ovulation rate prolificacy was also improved and a high proportion of twins were produced. We concluded that high fertility and low prolificacy (i.e. of 1.00) are an unlikely combination. In the final experiment the effect of post-mating hormonal supplementation on fertility was examined and a number of earlier reports were confirmed by showing that fertility can be improved with supplementary progesterone between days 10 and 25 post-mating. The effect appears to be modified by hormonal and nutritional factors.</p>","PeriodicalId":8573,"journal":{"name":"Australian journal of biological sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14209417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seasonality of reproduction in sheep and its control by photoperiod.","authors":"R Ortavant,&nbsp;F Bocquier,&nbsp;J Pelletier,&nbsp;J P Ravault,&nbsp;J Thimonier,&nbsp;P Volland-Nail","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Seasonality of the reproductive cycle in sheep is a general phenomenon for mid-latitude breeds. The proximal part (breeding season) and also partially distal part (end of gestation and beginning of lactation) of this cycle is controlled by photoperiod, whatever the form of light regimens. Data are presented which indicate that male and female do not necessarily have the same photoperiodic sensitivity. Gonadal stimulation in the ram starts 1.5-2 months earlier than in the ewe under annual variations. Photoperiod controls the reproductive cycle by the intermediary of the hypothalamo-pituitary axis. There are both a steroid-independent and a steroid-dependent effect of light, depending on both decreasing and increasing daylength in mid-latitudes. Data are also presented which support Bunning's hypothesis on photoperiodic time measurement in mammals. Sheep measure photoperiodic time by using a circadian rhythm of photosensitivity. Daylength is not measured by the total duration of exposure to light but by the illumination of two special set points during the day, one of them entraining the circadian rhythm of photosensitivity and the other inducing or not inducing a physiological response if it is coincident, or not coincident, with photoinducible phase of that rhythm. A photoinducible phase has been found for prolactin secretion, and perhaps also for LH secretion. Melatonin secretion is used by sheep for measuring daylength. However, that secretion disappears during two set points during the day, thus raising the possibility of using alternatively melatonin and light pulse for controlling the reproductive cycle in sheep.</p>","PeriodicalId":8573,"journal":{"name":"Australian journal of biological sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14209418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Are megabats flying primates? Contrary evidence from a mitochondrial DNA sequence.","authors":"S Bennett,&nbsp;L J Alexander,&nbsp;R H Crozier,&nbsp;A G Mackinlay","doi":"10.1071/bi9880327","DOIUrl":"https://doi.org/10.1071/bi9880327","url":null,"abstract":"","PeriodicalId":8573,"journal":{"name":"Australian journal of biological sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/bi9880327","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14396200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structure-activity studies of melatonin analogues in prepubertal male rats.","authors":"D J Kennaway,&nbsp;H M Hugel,&nbsp;S Clarke,&nbsp;A Tjandra,&nbsp;D W Johnson,&nbsp;P Royles,&nbsp;H A Webb,&nbsp;F Carbone","doi":"10.1071/bi9880393","DOIUrl":"https://doi.org/10.1071/bi9880393","url":null,"abstract":"<p><p>Comparison has been made between the activity of the pineal hormone melatonin, and several analogues and metabolites in inhibiting sexual development in a protein-restricted prepubertal rat model. Eleven melatonin analogues or metabolites were tested with the aim of evaluating the model as a test of the hypothesis that melatonin acts as a prohormone and that the ring schism metabolites (kynurenamines) mediate many of the effects attributable to melatonin. Although the hypothesis could not be confirmed, modification of the melatonin structure by lengthening the acrylamide side chain or by replacing the 5 methoxy function with fluorine resulted in loss of biological potency. Modification of the melatonin structure to block the two known points of metabolism resulted in no significant alteration in biological activity. Thus 6-chloromelatonin (blocking 6-hydroxylation) and 2,3-dihydromelatonin (blocking oxidative cleavage of the C2-C3 bond) and 6-chloro-2,3-dihydromelatonin remained biologically active. The metabolic products of brain indoleamine-2,3-dioxygenase, N-acetyl-N2-formyl-5-methoxy kynurenamine (aFoMK) and N-acetyl-5-methoxy kynurenamine (aMK), paradoxically were also biologically active.</p>","PeriodicalId":8573,"journal":{"name":"Australian journal of biological sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/bi9880393","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14397104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of sheep embryos in vitro in a medium supplemented with different serum fractions.","authors":"P A Batt,&nbsp;B G Miller","doi":"10.1071/bi9880189","DOIUrl":"https://doi.org/10.1071/bi9880189","url":null,"abstract":"<p><p>Sheep embryos will generally develop into expanded blastocysts in vitro only in culture media supplemented with serum or serum components. In order to better understand how serum supports embryo development, a batch of ovine serum was fractionated by (a) ultrafiltration into two components containing substances with molecular weights greater and less than 10 Kd (kilodaltons), and (b) gel filtration into protein fractions 1, 2 and 3, containing groups of proteins with mean molecular weights of about 500, 150 and 65 Kd, respectively. The principal protein in fraction 3 was albumin. Day 6 sheep morulae were cultured in vitro for 48 hours in a bicarbonate-buffered salt solution supplemented with various concentrations of ovine serum or of these components or protein fractions of serum. Morulae could develop to fully expanded blastocysts in medium supplemented with whole serum or with the greater than 10 Kd component or protein fraction 3 only, but could not develop in medium supplemented with the less than 10 Kd component only or with the less than 10 Kd component and protein fractions 1 or 2. However, the proportion of embryos that developed fully in medium supplemented with the greater than 10 Kd component or protein fraction 3 was increased by adding the less than 10 Kd component of serum to the medium. The addition of protein fraction 2 decreased the proportion of embryos that developed to expanded blastocysts in medium containing protein fraction 3 and the less than 10 Kd component, but not in medium containing whole serum. Since the compositions of different sera may vary markedly, these results suggest (a) reasons why different sera vary in their ability to support embryo development in vitro, and (b) factors which may influence development of the sheep embryo in the uterus, where plasma proteins comprise nearly all the protein in the fluid bathing the embryo.</p>","PeriodicalId":8573,"journal":{"name":"Australian journal of biological sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/bi9880189","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14398722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The fate of tritiated rm-epidermal growth factor in the sheep: validation of the labelling procedure and rate of tissue clearance.","authors":"J H O'Keefe,&nbsp;L F Sharry,&nbsp;B A Panaretto","doi":"10.1071/bi9880539","DOIUrl":"https://doi.org/10.1071/bi9880539","url":null,"abstract":"<p><p>Plasmid-derived recombinant mouse epidermal growth factor, rm-EGF, was purified by ion pair reversed phase high performance liquid chromatography. The product peak (termed rm-alpha-EGF) was characterized by physicochemical techniques including fast atom bombardment mass spectrometry, high field proton magnetic resonance and amino acid sequencing (amino acid arrangement and composition). The rm-alpha-EGF was tritiated, labile tritium removed by lyophilization, and the product purified and characterized as for the parent compound to yield a compound identical to rm-alpha-EGF except for the isotopic hydrogen substitution. Label stability was validated by lyophilization of samples, especially urine. The tritiated rm-alpha-EGF was used to determine the excretion rate and tissue distribution pattern in the sheep. It was administered by intravenous infusion for 24 h at a dose rate of 120 micrograms kg-1 live weight. Blood, urine and faeces were collected at frequent intervals from all sheep up to slaughter. Sheep were slaughtered at 24 h (3 sheep), 48 h (3 sheep), and 192 h (1 sheep) from the start of infusion and samples of all tissues and organs collected. Samples were assayed by liquid scintillation counting, directly for liquids, and after combustion to tritiated water for solids. For residue studies all solid samples were lyophilized to constant weight before combustion, and volatile tritium determined from the lyophilisate. Urinary excretion was extensive and rapid. From the start of the infusion 30.1% of the administered tritium was recovered at 24 h, 40.4% at 48 h and 55.1% at 192 h. Comparison of RIA and tritium (3H) in plasma and urine samples indicated that the EGF had undergone considerable metabolism. Faecal excretion of EGF was also significant, being 1.5% at 24 h, 2.1% at 48 h and 10.0% at 192 h after the start of the infusion. Of the EGF not excreted at the time of slaughter, 41.9% (24 h), 36.8% (48 h) and 22.1% (192 h) was present in eight locations: muscle, intestine, gut content, skin, blood, liver, kidney, and lung. Tritium in fat (omental, perinephric, subcutaneous) was negligible, and no 3H was detected in the plucked fleece 192 h after the start of the infusion. Volatile metabolic products (H2O, CH4, NH3) excreted via the lung were not measured. The overall recoveries of 97.4% (24 h), 100.5% (48 h), and 97.8% (192 h) confirm that the label was in stable positions. This result thus validates the labelling procedure and the use of a generally labelled compound, and confirms the efficacy of the sampling procedure.(ABSTRACT TRUNCATED AT 400 WORDS)</p>","PeriodicalId":8573,"journal":{"name":"Australian journal of biological sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14398838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Controlled breeding in the Asiatic buffalo (Bubalus bubalis).","authors":"I. Fletcher","doi":"10.1071/BI9880147","DOIUrl":"https://doi.org/10.1071/BI9880147","url":null,"abstract":"Recent developments in exogenous hormone therapy to control and facilitate breeding in domestic buffalo cows (B. bubalis) are reviewed. Oestrus in domestic animals was synchronized satisfactorily during the normal breeding season by both of the standard treatments with prostaglandins or progestagens initially developed for use in Bos taurus cattle. Anoestrous cyclic cows treated with prostaglandin showed synchronized oestrus and conception rates similar to those recorded in normal cyclic animals, though the responses may have depended to some extent on increased intensity of observation of oestrus. Seasonally acyclic animals treated with progestagens and pregnant mare serum gonadotrophin also showed synchronized oestrus and conception rates equivalent to those recorded in cyclic animals, but these observations did not include prepubertal heifers or cows in the early stages of post-partum anoestrus. Controlled breeding did not overcome a general problem of low conception rates at spontaneous oestrus. Further investigations of controlled breeding should incorporate other management strategies, such as better feeding and reduced heat stress, which are known also to improve buffalo reproduction.","PeriodicalId":8573,"journal":{"name":"Australian journal of biological sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76808642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ovulation in the merino ewe in the breeding and anoestrous seasons.","authors":"D. T. Pearce, C. Oldham","doi":"10.1071/BI9880023","DOIUrl":"https://doi.org/10.1071/BI9880023","url":null,"abstract":"The pattern of ovulation of Merino ewes was studied by repeated laparoscopy each 14 days in the anoestrous (n = 97) and breeding (n = 87) seasons. In the anoestrous season the proportion of ewes ovulating did not decrease below 11%, 42% of ewes never ovulated and the remainder fluctuated between the two states. On 20 occasions a clear anovulatory period was interrupted by an isolated spontaneous ovulation. In the breeding season the overall mean proportion of ewes with corpora lutea or albicantia at laparoscopy was 87%, 54% of ewes ovulated regularly throughout while in another 31% absence of corpora lutea or albicantia coincided with the follicular phase of an oestrous cycle as evidenced by an appropriately aged corpora lutea at the next laparoscopy. Of the remaining 15% of the flock 3% had anovulatory periods greater than 14 days while the remainder experienced irregular ovulatory cycles--the majority due to short periods of anovulation but some ewes retained corpora lutea for longer than 14 days while others ovulated twice between successive laparoscopies.","PeriodicalId":8573,"journal":{"name":"Australian journal of biological sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73560352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}