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PubMed1982

Control of ovulation in mares in the early breeding season with ovarian steroids and prostaglandin.

Two trials were conducted to (1) determine the degree of control of ovulation achieved by treating mares in late winter with progesterone and oestradiol-17 beta combined after prior exposure to an artificially increased photoperiod, and (2) to examine the effectiveness of such a procedure incorporated into equine breeding farm management systems. Following a 15-day treatment of 150 mg progesterone and 10 mg oestradiol-17 beta daily with 10 mg PGF-2 alpha on the last day of steroid treatment, 27 of 31 mares ovulated on Days 8-14 after the last injection in one trial. Conception rate for mares mated during that period was 77%, compared with 50% in untreated mares mated at first oestrus following the treatment period. In a second, larger field trial involving the same treatment for a 10-day period, 103 of 128 mares ovulated on Days 9-16 after the last injection and 62% of the mares mated on those days conceived. These results indicate that the combined steroid treatment provided reasonably precise and practical control of ovulation time in mares adequately stimulated by increased photoperiod without detrimental effect on fertility.

Animals↗
PubMed2002

Identification of post-vasectomy sperm auto-antigens in fox (Vulpes vulpes) by two-dimensional gel electrophoresis and Western blotting.

The aim of this work was to identify antigenic surface proteins on fox spermatozoa. Six foxes were inguitinally vasectomised, and the time course of antibody response in the sera was studied. Five out of the six foxes reacted to vasectomy with a production of antisperm antibodies. The number of bands recognised by Western blot was maximal 120-150 days after the vasectomy, at the end of the reproductive season. On the whole, 30 bands were recognised between 9 and 150 kDa. The pattern of recognised proteins varied from one fox to another. The humoral response was studied in one fox 2 years after the vasectomy, before, during and after the breeding season. The same proteins were recognised, but the intensity of staining was increased during the testis regression. Using FITC-labelling on sperm smears with fox sera, antigens were localised at or near the sperm surface, either on the acrosome or both on the acrosome and on the flagellum. Using two-dimensional gel electrophoresis and Western blotting, we identified eight areas containing major antigens, recognised by at least two sera. The molecular weights (kDa) and isoelectric points of the repeated antigens were, respectively [150, 6.6-6.0]; [105-98, 6.0-5.5]; [97, 4.6-4.3]; [95, 5.0]; [85-80, 5.4-5.1]; [42, 5.0-4.8]; [17-15, 6.5-5.9]; and [17-15, 5.5-4.8]. The results of this study can be used to characterise more precisely fox sperm auto-antigens by microsequencing the selected proteins.

Animals↗
PubMed1997

The efficacy of diagnostic laparoscopic ultrasound.

Precise staging of malignant disease is required to define the optimum therapeutic strategy. In spite of technical advances, the sensitivity of conventional imaging techniques is usually limited to defining lesions of at least 1 cm in size. Laparoscopy is a sensitive technique that is very valuable for visual inspection of the abdominal cavity and the identification of small surface lesions. However, non-superficial lesions may escape detection due to the lack of tactile sensitivity. As an adjunct to laparoscopy, this study, utilizing a young swine model, has analyzed the detectability of intra-abdominal lymph nodes by laparoscopic ultrasound (LU). Lymph nodes in and around the hepatoduodenal ligament, examined and measured by LU, were resected by subsequent open laparotomy in eight young, mixed-breed swine. The numbers and sizes of lymph nodes detected by LU and resected at laparotomy were compared and analyzed statistically. Forty-six lymph nodes were resected by laparotomy, while LU failed to detect 3 small nodes (sensitivity, 43/46 = 93.5%). The sizes of lymph nodes in the LU group correlated strongly with the sizes actually measured in the laparotomy group (r = 0.936, P < 0.001). Twenty-six small lymph nodes, which conventional extracorporeal imaging might have failed to diagnose, were detected accurately by LU (r = 0.877, P < 0.001). This new technology may not only be effective for staging intra-abdominal malignant disease, but adds the benefit of obtaining tissue samples under direct vision using minimally invasive techniques.

Abdomen↗
PubMedDate not supplied

A Bayesian model for assessing the frequency of multiple mating in nature.

Many breeding systems have multiple mating, in which males or females mate with multiple partners. With the advent of molecular markers, it is now possible to detect multiple mating in nature. However, no model yet exists to effectively assess the frequency of multiple mating (f(mm))--the proportion of broods with at least two males (or females) genetically contributing--from limited genetic data. We present a single-sex model based on Bayes' rule that incorporates the numbers of loci, alleles, offspring, and genetic parents. Two genetic criteria for calculating f(mm) are considered: the proportion of broods with three or more paternal (or maternal) alleles at any one locus and the total number of haplotypes observed in each brood. The former criterion provides the most precise estimates of f(mm). The model enables the calculation of confidence intervals and allows mutations (or typing errors) to be incorporated into the calculation. Failure to account for mutations can result in overestimates of f(mm). The model can also utilize other biological data, such as behavioral observations during mating, thereby increasing the accuracy of the calculation as compared to previous models. For example, when two sires contribute equally to multiply mated broods, only three loci with five equally common alleles are required to provide estimates of f(mm) with high precision. We demonstrate the model with an example addressing the frequency of multiple paternity in small versus large clutches of the endangered Kemp's Ridley sea turtle (Lepidochelys kempi) and show that females that lay large clutches are more likely to have multiply mated.

Animals↗
PubMed1989

[Body weight dynamics of laboratory white rats in the postnatal development period].

Dynamics of body mass has been followed in 663 noninbred animals from birth up to 3.5 years of age. The rats are kept in vivarium, taking into account necessary demands upon their diet, breeding, amount of the brood and sex dimorphism. The offspring is obtained with a strictly dated time of birth. During the first month of life they are weighed daily (up to a complete maturation, specimens of both sex are measured, till intensity of males and females growth is similar), and then with the interval, increasing as a geometrical progression, with a coefficient 1.1 up to the 1231st day after birth (males only). At every period of observations no less than 7 animals are examined, average mass and standard deviation are calculated. Dynamics of the parameters are determined by means of sliding average. Using the curves on the body mass changes in the laboratory rats during nearly their whole life, it is possible with a desired precise to determined their age at carrying out investigations of wide range on ontogenesis of organs and tissues, when the animals are bred in nurseries.

Aging↗
PubMed1993

Secretion and release of luteinizing hormone during the luteal phase of the oestrous cycle in the dog.

In order that the luteotrophic activity of luteinizing hormone (LH) in the dog might be more precisely elucidated, LH and progesterone were measured in blood samples collected at intervals of 10-15 min over 360 min from three beagle and two foxhound-boxer bitches at a defined day during pro-oestrus, the phase immediately after ovulation, early and late dioestrus and early anoestrus. In addition, the three beagle bitches were treated with the gonadotrophin-releasing hormone (GnRH) analogue buserelin at a given day during each quarter of dioestrus and blood was sampled over 480 min at intervals of 15 min (for 2 h), 30 min (for 4 h) and 60 min (for 2 h). Cyclic activity was monitored by determining progesterone at intervals of 1 or 2 days up to 140 days. In spite of some apparently breed-specific differences, the results indicated that the availability of LH depended on the stage of the cycle. The area under the curve (AUC) was higher during pro-oestrus, late dioestrus and early anoestrus (P < 0.01-0.05), largely as a result of an increased pulse amplitude and not of changes in basal concentrations or pulse frequency. After GnRH the AUC for the provoked LH release increased from 1206 ng (150 min) ml-1 (first quarter) to 4045 ng (150 min) ml-1 (fourth quarter) (P < 0.01); maximum LH values were reached between 25 and 40 min. In neither experiment did progesterone increase during the observation periods of 360 and 480 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2025

Cr3a, a candidate gene conferring fruit cracking resistance, was fine-mapped in an introgression line of Solanum lycopersicum L.

In the cultivation and production of tomato (Solanum lycopersicum L.), fruit cracking is a prevalent and detrimental issue that significantly impacts the esthetic quality and commercial value of the fruit. The complexity of the trait has resulted in a slow advancement in research aimed at identifying genes that influence tomato fruit cracking and the underlying regulatory mechanisms. In this study, a sub-introgression population for tomato crack-resistant fruit has been constructed from the cross between S. lycopersicum 1052 and Solanum pennellii LA0716, followed by 11 generations of selfing. Utilizing specifically designed InDel markers, the tomato crack-resistant gene, Cr3a, was fine-mapped, cloned, and its functionality was confirmed through transgenic and gene-knockout approaches. The precise localization of Cr3a was delineated to a 30&#x2009;kb genomic region on chromosome 3, corresponding to the gene Sopen03g034650 in S. pennellii and Solyc03g115660.3 in the Heinz1706 variety. An integrated transcriptomic and metabolomic analysis of fruits with and without the Cr3a gene was finally conducted to elucidate the intricate regulatory mechanisms associated with Cr3a. The findings revealed a molecular regulatory network for tomato fruit crack resistance, characterized by 7 key metabolites, 13 pivotal genes, and 4 critical pathways: the phenylpropanoid biosynthesis pathway, the phenylalanine, tyrosine, and tryptophan biosynthesis pathway, the linolenic acid metabolism pathway, and the cysteine and methionine metabolism pathway. In summary, this research provides novel insights into the molecular underpinnings of tomato fruit crack resistance and holds substantial promise for accelerating the molecular breeding of tomatoes with enhanced fruit crack resistance.

Solanum lycopersicum↗
PubMed2001

Application of a structural model for genetic covariances in international dairy sire evaluations.

A structural model for estimation of genetic covariances in international dairy sire evaluations was compared with a standard multiple-trait mixed model using milk yield data from 13 environments (Austria, Belgium, Czech Republic, Denmark, Estonia, Finland, Israel, Switzerland and five regions of the United States). Data consisted of 2,885,117 first-lactation records from daughters of 17,867 Holstein sires. Parameters of the structural model for genetic covariances included an intercept and measures of genetic, management, and climate similarity. Genetic similarity was defined as the ratio between the number of daughters of common bulls used in a given pair of regions and the total number of daughters of all bulls. The measure of management similarity was the ratio between the absolute value of the difference in average milk yield between two regions and the sum of these averages. Climate similarity was a function of the difference in heat indices between pairs of regions. Results showed that the structural model for the genetic covariances gave more precise estimates of the latter than the standard multivariate analysis because the number of parameters to be estimated in the genetic covariance matrix was reduced from 91 to 16. A comparison of the two models using a deviance information criterion (a measure of quality of fit) showed a slight superiority for the structural model. For the latter, the posterior means of the genetic correlations between environments ranged between 0.63 and 0.98.

Analysis of Variance↗
PubMed1985

Comparative toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in four (sub)strains of adult male rats.

Four (sub)strains of adult male rats were given single oral doses of various concentrations of TCDD to establish and compare the oral 30-day LD50 values. The strains of rats were Fischer (F/334N) supplied by Harlan Industries, Frederick Cancer Research Center, and Charles River Breeding Laboratories; and CD supplied by Charles River Breeding Laboratories. The Charles River/Fischer rats were most sensitive to TCDD (LD50 = 164, 95% confidence limits 104-217 micrograms/kg), the Frederick/Fischer and Charles River/CD rats were moderately sensitive to TCDD (LD50 = 303, 250-360; and 297, 240-360 micrograms/kg, respectively), and the Harlan/Fischer rats were most resistant to TCDD (LD50 = 340, 281-409 micrograms/kg). The mean times of death were from 24.5 +/- 1.0 to 28.3 +/- 0.5 days and the percentage body weight loss at death was 37.4 +/- 1.2 to 42.7 +/- 1.3%. One week after exposure of the Charles River/Fischer animal to 45 micrograms TCDD/kg (1/4 the established 30-day LD50 dose), the same serum profile was induced as previously observed in the Harlan/Fischer rat, which includes hypoglycemia, hypertriglyceridemia, and hypercholesterolemia. These results emphasize the importance of indicating the precise dose, strain of rat, and time after dosing before termination in reporting the effects of TCDD on a particular biological response.

Animals↗
PubMed2006

Fetal ultrasonography: biometric data from four African primate species.

BACKGROUND: Nonhuman primates are raised in large numbers in research centers and zoos. Reproductive monitoring is required to improve breeding performances. Ultrasonography is a safe method to determine gestational age and to estimate the date of parturition. However only few data are available in nonhuman primates. METHODS: Fetal biometric data were obtained throughout pregnancy on four African primate species, namely chimpanzee, gorilla, mandrill and patas monkey. Measurements included biparietal diameter, transverse abdominal diameter, femur and humerus length, external interorbital diameter, and fetal heart rate. Curves established from these data were compared with previously published data in chimpanzees and gorillas and with those for humans and other closely related primate species. RESULTS: The curves for the different hominids were very similar, while those for mandrills more closely resembled baboons and data for patas monkeys were comparable to those for macaques. CONCLUSIONS: These data, by providing a tool to evaluate precise gestational age, will be useful for centers raising these four primate species.

Animals↗
PubMed2006

Fine mapping of S32(t), a new gene causing hybrid embryo sac sterility in a Chinese landrace rice (Oryza sativa L.).

Ketan Nangka, the donor of wide compatibility genes, showed sterility when crossed to Tuanguzao, a landrace rice from Yunnan province, China. Genetic and cytological analyses revealed that the semi-sterility was primarily caused by partial abortion of the embryo sac. Genome-wide analysis of the linkage map constructed from the backcross population of Tuanguzao/Ketan Nangka//Ketan Nangka identified two independent loci responsible for the hybrid sterility located on chromosomes 2 and 5, which explained 18.6 and 20.1% of phenotypic variance, respectively. The gene on chromosome 5 mapped to the previously reported sterility gene S31(t), while the gene on chromosome 2, a new hybrid sterility gene, was tentatively designated as S32(t). The BC1F2 was developed for further confirmation and fine mapping of S32(t). The gene S32(t) was precisely mapped to the same region as that detected in the BC1F1 but its position was narrowed down to an interval of about 1.9 cM between markers RM236 and RM12475. By assaying the recombinant events in the BC1F2, S32(t) was further narrowed down to a 64 kb region on the same PAC clone. Sequence analysis of this fragment revealed seven predicted open reading frames, four of which encoded known proteins and three encoded putative proteins. Further analyses showed that wide-compatibility variety Dular had neutral alleles at loci S31(t) and S32(t) that can overcome the sterilities caused by these two genes. These results are useful for map-based cloning of S32(t) and for marker-assisted transferring of the neutral allele in hybrid rice breeding.

Base Pairing↗
PubMed2026

Analyzing Meiosis in Maize.

Meiosis is central to sexual reproduction and the main source of genetic diversity in plants. Understanding how meiotic processes are regulated has direct relevance to agriculture. As meiotic recombination is the vehicle of plant breeding, gaining the ability to influence recombination patterns can accelerate crop improvement. Maize is a powerful model for studying plant meiosis, thanks to its large chromosomes, well-developed genetics, and the availability of diverse cytogenetic and molecular tools. Insights gained from maize studies can extend to other species. In this review, we describe a variety of approaches for examining meiosis and meiotic recombination in maize. Cytological techniques, including protein immunolocalization and fluorescence in situ hybridization (FISH), enable visualization of chromosome structure and behavior, as well as crossover (CO) formation. Chromatin immunoprecipitation (ChIP) is used in meiosis research to determine locations of recombination proteins, identify recombination sites, and elucidate chromatin features, such as histone modifications. Quantification of COs at specific genomic sites through pollen typing by droplet digital PCR allows precise high-resolution measurement of recombination rates. Combining cytology, protein localization, and molecular assays provides a multiscale picture of meiosis, linking molecular mechanisms to chromosome behavior and, ultimately, to genetic variation.

Journal Article↗
PubMed2004

Quantitative trait loci mapping for dairy cattle production traits using a maximum likelihood method.

A maximum likelihood method was developed for QTL mapping in half-sib designs and compared to the regression method in analyses of both field and simulated data. The field data consisted of milk production evaluations of 433 progeny tested sons of 6 sires and 64 microsatellite markers distributed over 12 chromosomes. Based on permutation tests, 5 significant QTL were detected in the field data by the regression method compared with 10 by the maximum likelihood method (P < 0.05). In field data analysis, the maximum likelihood method detected more significant QTL and had a smaller residual variance than the regression method. The simulation included 9 scenarios differing in number of families, family size, QTL variance, and marker density, each replicated 100 times. The simulation results suggested that, as for the regression method, the precision of estimating QTL from the maximum likelihood method improves with increasing number of sons per sire, increasing the ratio of QTL to phenotypic variance, and decreasing marker interval. The maximum likelihood method had a smaller dispersion of estimated QTL positions than the regression method in 6 of 9 scenarios simulated. Overall, the maximum likelihood method shows potential advantage in QTL detection over the regression method, especially in the situations with less favorable conditions for QTL detection.

Algorithms↗
PubMed1974

Population dynamics and age grading of mosquitos.

The dynamics of a vector population follows a characteristic pattern determined by the normal or modified environmental conditions of the biotope and by vector behaviour. The wide use of the precise method of age grading developed by Detinova and Polovodova has led to the conclusion that the dynamics of the various age groups may indicate behavioural, environmental, and epidemiological trends and changes and their significance. Age grading is useful for the qualitative assessment of vector density in general and of man-mosquito contact from the operational and epidemiological points of view, but only when sampling in time and space and the processing of the material collected have been correctly performed.

Age Factors↗
PubMed2000

Active spermiophagy in the initial part of the proximal efferent duct of the epididymis of normal domestic fowl (Gallus domesticus).

In a study of the absorptive activities of the excurrent ducts of the testis of birds, six adult cocks of the Ovambo breed of domestic fowl were deeply anaesthetised and intravascularly perfused with buffered 3 per cent glutaraldehyde. Epididymal tissue was prepared conventionally for electron microscopy. In favourable sections in three of these birds avid ingestion of spermatozoa was revealed in the non-ciliated (Type I) cells of the epithelial lining of the initial part of the proximal efferent duct, at and a little beyond its junction with the rete testis. No obvious defects were detected in luminal spermatozoa. The testicular excurrent ducts were neither distended nor obstructed, and mononuclear cell mobilisation was absent in both the ductal and periductal tissue. The significance of this observation with regard to the specific segment of the efferent duct system involved and how certain spermatozoa are identified for elimination from the duct lumen, must await precise studies.

Animals↗
PubMed2004

Distribution of Activator (Ac) throughout the maize genome for use in regional mutagenesis.

A collection of Activator (Ac)-containing, near-isogenic W22 inbred lines has been generated for use in regional mutagenesis experiments. Each line is homozygous for a single, precisely positioned Ac element and the Ds reporter, r1-sc:m3. Through classical and molecular genetic techniques, 158 transposed Ac elements (tr-Acs) were distributed throughout the maize genome and 41 were precisely placed on the linkage map utilizing multiple recombinant inbred populations. Several PCR techniques were utilized to amplify DNA fragments flanking tr-Ac insertions up to 8 kb in length. Sequencing and database searches of flanking DNA revealed that the majority of insertions are in hypomethylated, low- or single-copy sequences, indicating an insertion site preference for genic sequences in the genome. However, a number of Ac transposition events were to highly repetitive sequences in the genome. We present evidence that suggests Ac expression is regulated by genomic context resulting in subtle variations in Ac-mediated excision patterns. These tr-Ac lines can be utilized to isolate genes with unknown function, to conduct fine-scale genetic mapping experiments, and to generate novel allelic diversity in applied breeding programs.

Chromosome Mapping↗
PubMed2002

Fruit plant germplasm characterisation using molecular markers generated in RAPD and ISSR-PCR.

The genotypes of the strawberry (Fragaria x ananassa), apple (Malus domestica) and Ribes species (R. nigrum, R. rubrum and R. glossularia), maintained in our Institute's collection and used in breeding programs, were screened for DNA markers. Twenty primers for RAPD (among 60 tested) and seven for ISSR (among 10 tested) were chosen as creating polymorphic DNA bands differentiating the investigated genotypes. Based on those identity markers, the genetic distance between genotypes was determined, and their relatedness was estimated. In many cases, both RAPD- and ISSR-based genetic similarity confirmed relatedness connected with biological origin and with the place where the cultivar was developed. However, some diversity connected with the technique used for molecular marker generation was observed. Generally, the similarity values based on ISSR data were higher than those based on RAPD. Parallel study using two data sets seems to enable a reduction in the number of potential mistakes connected with each method's, technical limitations and ensures more precise relatedness determination.

DNA Fingerprinting↗
PubMed2000

Expansion of mouse involucrin by intra-allelic repeat addition.

Involucrin, loricrin and the small proline-rich proteins (SPRRs) are precursors of the cornified envelope of terminally differentiated keratinocytes. The genes for these proteins are closely linked on mouse chromosome 3. Each of the proteins is encoded by a single exon and is largely composed of a segment of short tandem repeats. No size polymorphism of either loricrin or the SPRRs was observed. In contrast, involucrin was found in at least eight polymorphic forms of different size with molecular weights ranging from 51 to 82kDa. Two classes of involucrin alleles were identified. Size polymorphism of involucrin has resulted from the recent expansion of the segment of repeats in one class of alleles, but not in the other. In expanding alleles, repeats were added at a precise location within the segment of repeats, in a 5'-to-3' direction. A study of a large number of allele-specific markers, located on both sides of the site of repeat addition, revealed no evidence for recombination between any of the alleles examined. Expansion of the segment of repeats of the gene for mouse involucrin must result from an intra-allelic process controlled by a cis-acting element, active in one class of alleles, and inactive in the other.

Alleles↗