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At least 1,243 records · Page 69Linked to original sources
PubMed2006

Breeding for disease resistance in the major cool-season turfgrasses.

Over the past several decades, breeding cool-season turfgrasses for improved disease resistance has been the focus of many turfgrass breeding programs. This review article discusses the dramatic improvements made in breeding Kentucky bluegrass (Poa pratensis) for resistance to leaf spot (caused by Drechslera poae), stem rust (caused by Puccinia graminis), and stripe smut (caused by Ustilago striiformis); perennial ryegrass (Lolium perenne) for resistance to gray leaf spot (caused by Pyricularia grisea), stem rust and crown rust (caused by Puccinia coronata); tall fescue (Festuca arundinacea) for resistance to brown patch (Rhizoctonia solani) and stem rust; creeping bentgrass (Agrostis stolonifera) for resistance to dollar spot (caused by Sclerotinia homoeocarpa); and fine fescues (Festuca spp.) for improved disease resistance. Historically, the dramatic improvements in disease resistance of the cool-season grasses have been attributed to traditional/conventional breeding techniques; however, it is likely that functional genomics and molecular techniques will play a more significant role in the development of cultivated turfgrasses as the specific genes and mechanisms for disease resistance are identified in the future.

Fungi↗
PubMed2000

Molecular breeding of allergy vaccines and antiallergic cytokines.

Molecular breeding, also called DNA shuffling, is a technology that enables the generation of large libraries of novel genes and vectors, from which improved variants can be selected based on functional properties. In a common format, it involves recursive recombination and mutation, performed by random fragmentation of related DNA sequences, followed by reassembly of the fragments in a self-priming polymerase chain reaction. As in natural evolution, the technique takes advantage of crossovers, deletions, insertions, inversions and point mutations of genes to generate large pools of related sequences. Molecular breeding can be used to generate improved variants of proteins used as therapeutics, such as vaccine antigens, growth factors and immunomodulatory molecules. Moreover, the technology can be applied to evolve entire viruses or vectors, including DNA vaccines. Cytokines downregulating allergic immune responses and allergens are attractive targets for evolution by molecular breeding. This review describes approaches to generate chimeric allergens with T cell epitopes from multiple allergen homologues, while reducing the recognition by preexisting IgE. In addition, the results and applications of molecular breeding in the evolution of improved antiallergic cytokines are discussed.

Allergens↗
PubMedDate not supplied

Multiple breeding females in captive groups of golden-headed lion tamarins (Leontopithecus chrysomelas): causes and consequences.

In Callitrichidae, reproduction in subordinate females is generally inhibited but occurs in rare cases, possibly in association with the presence of an unrelated male, important food resources or low dispersal opportunities. This study investigates the occurrence of groups with multiple breeding females in captive golden-headed lion tamarins (Leontopithecus chrysomelas), the factors leading to their formation and the consequences for the group. Information obtained from studbook data on the world captive population during 1984-1998 revealed that polygynous groups in captivity are very rare: only 7 cases were discovered. Family groups in which daughters started breeding with a related male were larger than average, had a high number of sexually mature sons and eldest offspring that were well past the age of sexual maturity. Following a breeding attempt, severe aggression frequently occurred, especially if the infants were liveborn. Polygynous groups composed of two related females and an unrelated male tended to remain stable for a longer period than families with breeding daughters. Competition for infant care is probably an important factor determining whether the polygynous situation can persist and for how long.

Age Factors↗
PubMed2000

Oestrogen receptor beta is not present in the pilosebaceous unit of red deer skin during the non-breeding season.

Androgens and oestrogens both have roles in skin physiology. Recently a second oestrogen receptor (ERbeta) has been identified in androgen-dependent tissues. The red deer grows a breeding season, androgen-dependent mane when plasma testosterone rises; this is replaced with small neck hairs during the non-breeding season. In non-breeding season deer skin, ERbeta was localised to the blood vessels and arrector pili muscle, but in contrast to human skin, not in the pilosebaceous unit or epidermis. The androgen receptor was not expressed. Further studies with breeding season skin may help to elucidate whether serum androgens or androgen receptor expression can modulate the expression of ERbeta in skin.

Animals↗
PubMedDate not supplied

Cerebral prothrombotic state in spontaneously hypertensive rats of different breeds.

The thrombotic tendency in two breeds of spontaneously hypertensive rats (SHRs) was assessed by inducing occlusive thrombosis in pial blood vessels using a helium-neon laser method. A prothrombotic state was observed in the SHR of one breed as compared to the corresponding control WKY, but not in the other. Circulating platelet and erythrocyte counts and haematocrit values were significantly negatively correlated in arterioles with the number of laser pulses, which is an index of the thrombotic tendency, suggesting that the prothrombotic state was partly dependent on the counts of blood components. However, there was no correlation between the measured blood parameters and prothrombotic state in venules. The difference observed in arterioles and venules might be due to their differential haemodynamics and endothelial properties. Prothrombotic state in the SHR of one breed would be partly due to the much higher difference in blood components from its corresponding control compared to the comparatively less difference in the other breed.

Animals↗
PubMed2000

The coincidence of light and melatonin with a specific phase of the circadian pacemaker is important for the timing of seasonal breeding in the ewe.

The timing of reproductive activity in seasonal breeding sheep relies on daily photoperiodic signals being relayed to provide information on the time of year. Although light and melatonin are involved, the exact mechanism is not understood. In this experiment, three groups of 6 Romney Marsh ewes, a highly seasonal breed, were provided with 8 weeks of short nights (9.6-9.8 h, by artificially advancing dawn) around the winter solstice, near the end of their natural breeding season. One group of animals was infused to a physiological level with melatonin for 5 h during the afternoon prior to the onset of dark, while a second group was identically infused but for 5 h from the time of lights on. A third group received the short-night treatment only. Following the short-night treatment, all groups were exposed to long nights (> 14 h, by delaying dawn) until the summer solstice. Ovarian activity, assessed by progesterone monitoring twice weekly, showed that the noninfused and the morning-infused groups displayed renewed reproductive activity in response to the short-night/long-night treatment. There was no renewed ovarian activity in the afternoon-infused group, indicating that the time of day that melatonin is present, rather than the duration of melatonin exposure, is an important signal in the control of reproductive timing. Measurements of a marker of the endogenous circadian pacemaker, by melatonin measurements under acutely extended darkness, revealed that the short-night treatments phase advanced the onset of the pacemaker in all groups such that the afternoon phase of the pacemaker was coincident with light. The results provide strong support for the model that proposes that an afternoon-located sensitive phase of the pacemaker is responsible for the relay of photoperiodic signals in the timing control of seasonal breeding. The model proposes that the reproductive axis be primed during short nights when the sensitive phase is coincident with light in the afternoon so ovarian activity can be induced when the sensitive phase is located within the longer nights of autumn and coincident with endogenous melatonin.

Animals↗
PubMedDate not supplied

Haplotype diversity of the myostatin gene among beef cattle breeds.

A total of 678 individuals from 28 European bovine breeds were both phenotyped and analysed at the myostatin locus by the Single Strand Conformation Polymorphism (SSCP) method. Seven new mutations were identified which contribute to the high polymorphism (1 SNP every 100 bp) present in this small gene; twenty haplotypes were described and a genotyping method was set up using the Oligonucleotide Ligation Assay (OLA) method. Some haplotypes appeared to be exclusive to a particular breed; this was the case for 5 in the Charolaise (involving mutation Q204X) and 7 in the Maine-Anjou (involving mutation E226X). The relationships between the different haplotypes were studied, thus allowing to test the earlier hypothesis on the origin of muscular hypertrophy in Europe: muscular hypertrophy (namely nt821(del11)) was mainly spread in different waves from northern Europe milk purpose populations in most breeds; however, other mutations (mostly disruptive) arose in a single breed, were highly selected and have since scarcely evolved to other populations.

Animals↗
PubMedDate not supplied

Evolutionary relationships of Red Jungle Fowl and chicken breeds.

Published results were reassessed and original data are provided regarding the origin and relatedness of four postulated chicken breed lineages, egg-type, game, meat-type and Bantam, to each other and to the basic ancestral species of jungle fowls, Gallus gallus. A system approach was employed concerning the planning of the experiments. One element of the system approach is the choice of the breeds to be compared with G. gallus. These breeds were supposed to represent major evolutionary branches of chickens. Four experiments on genetic relationships were conducted using different estimation criteria including morphological discrete characters, body measurements, biochemical markers, and the activity of serum esterase-1. The greatest similarity was found between G. gallus and the egg-type breeds of Mediterranean roots and/or true Bantams. This fact might testify that the indicated chicken groups occupied earlier stages in the evolution from the wild progenitor to the present biodiversity of chickens in the world.

Animals↗
PubMed2006

DGAT1 and ABCG2 polymorphism in Indian cattle (Bos indicus) and buffalo (Bubalus bubalis) breeds.

BACKGROUND: Indian cattle (Bos indicus) and riverine buffalo (Bubalus bubalis) give a poor yield of milk but it has a high fat and protein percentage compared to taurine cattle. The identification of QTLs (Quantitative Trait Loci) on BTA14 and BTA6 and its subsequent fine mapping has led to identification of two non conservative mutations affecting milk production and composition. Our objective was to estimate the frequency of K232A (DGAT1--diacylglycerol-acyltransferase 1) and Y581S (ABCG2--ATP binding cassette sub family G member 2) polymorphisms in diverse cattle and buffalo breeds of India having large variation in terms of milk production. RESULTS: We screened the reported missense mutations in six cattle and five buffalo breeds. The DGAT1K and ABCG2Y alleles were found to be fixed in Indian cattle and buffalo breeds studied. CONCLUSION: This study provides an indirect evidence that all the Indian cattle and buffalo breeds have fixed alleles with respect to DGAT1 and ABCG2 genes reported to be responsible for higher milk fat yield, higher fat and protein percent.

ATP-Binding Cassette Transporters↗
PubMed1997

Breed differences in expression of inhibin/activin subunits in porcine anterior pituitary glands.

Chinese Meishan (MS) boars have greater plasma FSH concentrations than European White Composite boars, but this difference does not occur in females of these breeds. To understand this disparity, we studied expression of the follistatin gene and of genes for the inhibin/activin alpha-, beta A-, and beta B-subunits in porcine anterior pituitary glands using quantitative reverse transcription-PCR and ribonuclease protection techniques. We found that 1) the inhibin/activin beta A- and beta B-subunits and follistatin were expressed in porcine pituitary, 2) the alpha-subunit was not detected in the porcine pituitary, but was highly expressed in porcine follicles; and 3) the beta B-subunit gene is more abundantly expressed (2-fold greater) in MS boar pituitaries than in pituitaries of White Composite boars. We conclude that this is not due to a breed difference, because the expression levels of this gene were similar in pituitaries of females of these breeds. No breed differences were detected for other genes screened in this study. From these observations, we propose that activin B, a dimer of beta B-subunits and a stimulator of FSH secretion, may be partially responsible for the elevated plasma FSH concentrations in MS boars, and intrapituitary inhibin plays no or a very minimal role.

Activins↗
PubMed2003

Plasma concentration of estrone sulfate during pregnancy in different breeds of Japanese beef cattle.

Plasma concentrations of estrone sulfate in different breeds of Japanese beef cattle and the relationship between those concentrations and feto-placental growth were examined in order to assess the possibility of monitoring abnormal growth of the fetus. Blood samples were obtained from cows from day 90 of gestation to parturition. The plasma concentration of estrone sulfate was measured by direct enzyme immunoassay. From day 180 of gestation, the mean concentration of estrone sulfate increased gradually and it was drastically elevated after day 240 of gestation with the maximum at day 285. Plasma concentrations of estrone sulfate on day 240 of gestation was significantly increased in F(1) cows (Holstein Friesian and Japanese Black) compared with those in other breeds of cow. From day 270 to 278 of gestation, estrone sulfate concentrations of Holstein Friesian cows inseminated by Holstein Friesian differed from those inseminated by Japanese Black. In the cow with retained placenta, the plasma concentration of estrone sulfate reached plateau at day 240 of gestation and did not increase thereafter. There was no significant relationship between estrone sulfate concentration and duration of gestation, calf birth weight, weight of placenta or viability of newborn calves. These results indicate that changes of plasma estrone sulfate concentration in Japanese beef cattle are very similar to those in Holstein dairy cattle. They also suggest that the plasma concentration of estrone sulfate is associated with the breed of pregnant cow and that its concentration is also affected by calf birth weight depending on the breed of bull. It seems possible to predict the incidence of retained placenta but not the calf birth weight and viability of newborn calves in Japanese beef cattle.

Animals↗
PubMed1998

Relationship between plasma testosterone concentrations and age, breeding season and harem size in Misaki feral horses.

Jugular vein blood samples were collected from 23 young and sexual mature feral stallions to examine the relationship between plasma testosterone concentration and age, breeding season or harem size. Testosterone concentration increased with the age of the stallions until they formed their own harems, at about 4 to 6 years old. Seasonal variations in testosterone concentrations were observed, and found to be significantly higher (P<0.001) throughout the breeding season than non-breeding season, from 3 years of age. Testosterone levels were correlated with harem size for individual stallions. It can be inferred from these results that there is a relationship between plasma testosterone concentration and age, breeding season and harem size.

Age Factors↗
PubMed2004

Allele frequency distribution of the canine dopamine receptor D4 gene exon III and I in 23 breeds.

Various canine breeds are remarkably different from each other not only in their sizes and shapes but also in behavioral traits, suggesting that some of them are under genetic control. Although dopaminergic neurotransmission system is considered to affect animal behavior, little is known about related genes in canine. Relations between specific alleles in polymorphic regions of the dopamine receptor D4 gene (DRD4) and personality or psychiatric disorders have been reported in humans, and we first found polymorphism in exon III region of the gene in 4 canine breeds. In this study we surveyed allele frequency distribution in 23 breeds including a total of 1,535 unrelated individuals. In exon III, 8 alleles including a novel allele were identified. A group of breeds in which the alleles 447b, 498 and 549 were frequent tended toward high scores in aggression-related behavioral traits than that with frequent alleles 435 and 447a. Moreover, a polymorphism based on 24 bp insertion/deletion was found in exon I region for the first time in dogs. This information may be of use for candidate gene studies of behavioral variation in dogs.

Amino Acid Sequence↗
PubMed2005

Clinicopathological survey of 101 canine mammary gland tumors: differences between small-breed dogs and others.

Clinicopathological features of mammary gland tumors (MGTs) in 101 dogs were evaluated retrospectively. The incidence of histological malignancy in 60 small- and 41 other-breed dogs were 25% and 58.5%, respectively. In 82 epithelial MGTs, small-sized tumors (< 3 cm) or non-invasive tumors were predominant in small breeds. In multivariate survival analysis, small breed (p=0.048) and lower stage of tumor cell invasion (p=0.006) were significantly associated with longer survival time. These results suggest that the incidence of histological or biological malignancy in MGTs is lower in small-breed dogs than in others.

Animals↗
PubMed1989

Evidence that the seasonally breeding Bennett's wallaby (Macropus rufogriseus rufogriseus) does not exhibit short-day photorefractoriness.

Adult female Bennett's wallabies (N = 6) were maintained in artificial winter solstitial daylengths commencing 3 weeks before the winter solstice for 16 or 42 weeks. Such treatment effectively prevented the normal establishment of seasonal reproductive quiescence with animals continuing to exhibit reproductive cycles beyond the time of the normal termination of the breeding season. Animals maintained in natural photoperiods or simulated natural changes in daylength after the winter solstice all entered reproductive quiescence by early February. In the Bennett's wallaby, therefore, the breeding season does not terminate as a result of refractoriness to short daylengths. Our results indicate that the relatively small increases in photoperiod shortly after the winter solstice provide the environmental signal responsible for initiating the onset of seasonal reproductive quiescence which normally occurs 5-8 weeks after the solstice. These results contrast with the effect of fixed artificial summer solstitial daylengths on the onset of the breeding season in which breeding begins spontaneously at the normal time of year as a result of long-day photorefractoriness.

Animals↗
PubMed1992

The role of photoperiod on the initiation of the breeding season of the brushtail possum (Trichosurus vulpecula).

The role of photoperiod on the initiation of the breeding season of brushtail possums was investigated in possums housed in three light regimens: a short-day, a natural and a long-day photoperiod. Seven possums were housed in a natural photoperiod. Four possums were transferred to a short-day photoperiod (10 h light, 14 h dark) and eight possums to a long-day photoperiod (14 h light, 10 h dark) on 22 November, when the daylength was 13.34 h. The first rises in plasma progesterone concentrations were observed on 9 January +/- 9 days (n = 4), 11 March +/- 6 days (n = 7) and 6 May +/- 6 days (n = 8), for possums held in short-day, natural or long-day photoperiods respectively. Similarly, births were observed on 12 January and 14 February in the short-day group, from 3 March to 8 May for the natural photoperiod group, and from 5 May to 8 August for the long-day group. These results suggest that photoperiod is important in the timing of the breeding season. However, annual breeding will commence in a nonstimulatory long-day photoperiod. Thus a long-day photoperiod does not prevent breeding activity.

Animals↗
PubMed1997

Ovarian follicular dynamics in ewes during the transition from anoestrus to the breeding season.

Daily transrectal ovarian ultrasonography was performed in ten ewes for 5 consecutive days, once in early July, once in late July (anoestrus) and then continuously until from mid-August until ewes had completed one ovulatory cycle. During anoestrus the size range and numbers of ovarian antral follicles were similar to those seen during the breeding season. However, numbers of small antral follicles (2-3 mm in diameter) decreased during late anoestrus, and maximum follicle diameter increased just before the short period of progesterone secretion preceding the first observed ovulation. The ovarian antral follicles that ovulated first and second in the breeding season grew from 2 mm in diameter to 5.7 +/- 0.3 mm and 6.2 +/- 0.3 mm diameter over 4.7 +/- 0.3 days and 4.6 +/- 0.3 days, respectively, and the interovulatory interval was 16.6 +/- 0.2 days. During the first ovulatory cycle, follicles emerged to grow from the 2 mm size class on 11 of the 17 days, but peaks of emergence were seen on days 2 and 11. The first observed ovulation was preceded by a transient increase in serum concentrations of progesterone (6 days duration), with a peak concentration of 1.30 +/- 0.22 nmol l-1. With ultrasonography, no evidence of ovulation was seen before the increase in progesterone secretion and no luteal structures was detected during the small increase in progesterone secretion; however, luteal structures are normally detected by ultrasonography only from 3 to 5 days after ovulation. An LH surge similar to a preovulatory LH surge preceded the first increase in progesterone secretion in five ewes. Oestrus occurred consistently with ovulation only at the second observed ovulation of the breeding season, after a normal luteal phase. LH pulse frequency and mean and basal serum concentrations of LH all increased in late anoestrus, but no major trends in serum concentrations of FSH and oestradiol were seen during this period. It was concluded that at the end of anoestrus there is not major change in ovarian antral follicle dynamics. At this time, increased LH secretion was seen as was a reduction in numbers of small antral follicles and a greater maximum diameter of follicles. A surge release of LH resulted in a short-lived secretion of progesterone, the source of which was unclear; this was followed by the first observed ovulation and the first ovulatory cycle of the breeding season. Oestrus occurred consistently only at the second observed ovulation of the season and the peak concentration of progesterone at each period of progesterone secretion increased to at least the second ovulatory cycle.

Anestrus↗
PubMed2002

Partial cloning and polymorphism of the melatonin1a (Mel1a) receptor gene in two breeds of goat with different reproductive seasonality.

The melatonin1a (Mel1a) receptor gene was cloned in two breeds of goat, one with marked seasonal ovarian activity (Alpine breed) and the other with low seasonal variations in ovulatory activity (Creole breed), to determine whether reproductive seasonality is related to the structure of the Mel1a gene. The main part of exon II was amplified by PCR using sheep sense and antisense primers in 17 Alpine and 13 Creole goats, and cDNAs were subcloned and sequenced in both directions. The results indicate the presence of an identical sequence in 12 of the 30 animals, that is, six Alpine and six Creole goats. The greatest similarity in the 784 nucleotides of exon II (primers excluded) that was obtained was found with ovine Mel1a receptor sequence (98.4%) and the differences consisted of 12 nucleotide and four amino acid changes. The presence of seven mutations compared with the previous reference sequence was observed and their combinations indicated the presence of at least five other alleles; one mutation resulted in a change in one amino acid in three Alpine goats. No difference in allelic distribution was observed between the two breeds. The results indicate that no relationship could be established between the Mel1a receptor gene structure and the expression of seasonality of reproduction in goats.

Amino Acid Sequence↗