981 resultados para Breeding System


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The various types of pig farming, intensive and extensive, expose them to pig parasites but also to those from the environment of the breeding site. In this work was evaluated the exposure of bigs bred in technified farms, SISCAL (intensive breeding system in pens) and not technified (backyard) to leptospira, ticks and rickettsiae. Blood sera were analyzed to determine titers of antibodies anti-Leptospira by SAM technique and antibodies anti-rickettsial by IFA, pigs were inspected for ticks and in their breeding environment and surrounding areas (pastures and riparian vegetation), ticks were collected by the flannel dragging technique. In the farms of pigs 10.4% had anti-Leptospira antibodies, followed by SISCAL (8%) and backyard animals (2.5%). The serovars found were Bratislava, Pomona, serovar, Canicola and Icterohaemorrhagiae. Higher percentage of properties with pigs raised outdoors (SISCAL) had tick infested animals (20%) than those raised in backyard (6.7%), while commercial farms had no infested pigs nor infested breeding place. In both SISCAL and backyard pig breeding properties ticks were observed at the breeding site environment. Tick infestations were detected in areas surrounding pig breeding site in all three husbandry suystems. Ticks found were all Amblyomma scultpum nymphs or adults with the exception of one of Amblyomma parvum adult. In relation to anti-rickettsia serology to five Rickettsia species, 55.2% of pigs from commercial farms reacted to al least one species, backyard pigs reacted to 89.7% and all pigs of SISCAL showed anti-rickettsia titers. Consecutive tick sampling (June 2014 to February 2016) in SISCAL FAZU in Uberaba, showed the establishment A. sculptum ticks maintained by domestic pigs. These observations demonstrate the ability the pigs to maintain populations of A. sculptum at a favorable environment and may indicate a new trend in environmental infestations by this species of tick. Exposure to Leptospira and Rickettsia demonstrated the potential pigs exposure and transmission of important diseases in public health.

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Although the majority of passerine birds are socially monogamous, true genetic monogamy is rare, with extra-pair paternity (EPP) occurring in almost 90% of surveyed socially monogamous species. We present the first molecular data on the genetic breeding system of the long-tailed finch, Poephila acuticauda, a grass finch endemic to the tropical northern savannah of Australia. Although the species forms socially monogamous pair bonds during the breeding season, we found that extra-pair males sired 12.8% of 391 offspring, in 25.7% of 101 broods. Our findings provide only the second estimate of extra-pair paternity in the estrildid finch family.

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The present investigation examined the extracutaneous pigmentation pattern of three species of anuran amphibians, Dendropsophus nanus, Physalaemus cuvieri, and Rhinella schneideri, during the course of their breeding seasons. Pigmentation intensity in the different organs was graded on a 4-category scale, in which category 0 refers to organs without pigment and category 3 refers to intensely pigmented organs, with 2 intermediate stages of progressively stronger pigmentation. Rhinella schneideri showed testicular pigmentation, with intra-specific variation (categories 0 and 1). In P. cuvieri the pigmentation in the lungs varied in time: all the animals showed pigmentation (category 1) at the beginning of the breeding season, and as the season progressed the absence of pigments became the most common pattern. In the liver of the first animals collected, the pigment intensity was high (category 2) with many iridophores present, but in the last specimens collected no iridophores were found. The variation in D. nanus occurred in the kidneys, where animals collected at the beginning of the season did not show pigmentation. Renal veins displayed few melanocytes (category 1); animals collected at the end of the season showed more pigmentation in the kidneys (category 2), whereas in the renal veins the intensity remained the same. The changes observed in the extracutaneous pigment system in some organs, during the reproductive period, may be due to physiological alterations or may represent a species-specific characteristic.

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Sorghum (Sorghum bicolor (L.) Moench) is the world’s fifth major cereal crop and holds importance as a construction material, food and fodder source. More recently, the potential of this plant as a biofuel source has been noted. Despite its agronomic importance, the use of sorghum production is being constrained by both biotic and abiotic factors. These challenges could be addressed by the use of genetic engineering strategies to complement conventional breeding techniques. However, sorghum is one of the most recalcitrant crops for genetic modification with the lack of an efficient tissue culture system being amongst the chief reasons. Therefore, the aim of this study was to develop an efficient tissue culture system for establishing regenerable embryogenic cell lines, micropropagation and acclimatisation for Sorghum bicolor and use this to optimise parameters for genetic transformation via Agrobacterium-mediated transformation and microprojectile bombardment. Using five different sorghum cultivars, SA281, 296B, SC49, Wray and Rio, numerous parameters were investigated in an attempt to establish an efficient and reproducible tissue culture and transformation system. Using immature embryos (IEs) as explants, regenerable embryogenic cell lines (ECLs) could only be established from cultivars SA281 and 296B. Large amounts of phenolics were produced from IEs of cultivars, SC49, Wary and Rio, and these compounds severely hindered callus formation and development. Cultivar SA281 also produced phenolics during regeneration. Attempts to suppress the production of these compounds in cultivars SA281 and SC49 using activated charcoal, PVP, ascorbic acid, citric acid and liquid filter paper bridge methods were either ineffective or had a detrimental effect on embryogenic callus formation, development and regeneration. Immature embryos sourced during summer were found to be far more responsive in vitro than those sourced during winter. In an attempt to overcome this problem, IEs were sourced from sorghum grown under summer conditions in either a temperature controlled glasshouse or a growth chamber. However, the performance of these explants was still inferior to that of natural summer-sourced explants. Leaf whorls, mature embryos, shoot tips and leaf primordia were found to be unsuitable as explants for establishing ECLs in sorghum cultivars SA281 and 296B. Using the florets of immature inflorescences (IFs) as explants, however, ECLs were established and regenerated for these cultivars, as well as for cultivar Tx430, using callus induction media, SCIM, and regeneration media, VWRM. The best in vitro responses, from the largest possible sized IFs, were obtained using plants at the FL-2 stage (where the last fully opened leaf was two leaves away from the flag leaf). Immature inflorescences could be stored at 25oC for up to three days without affecting their in vitro responses. Compared to IEs, the IFs were more robust in tissue culture and showed responses which were season and growth condition independent. A micropropagation protocol for sorghum was developed in this study. The optimum plant growth regulator (PGR) combination for the micropropagation of in vitro regenerated plantlets was found to be 1.0 mg/L BAP in combination with 0.5 mg/L NAA. With this protocol, cultivars 296B and SA281 produced an average of 57 and 13 off-shoots per plantlet, respectively. The plantlets were successfully acclimatised and developed into phenotypically normal plants that set seeds. A simplified acclimatisation protocol for in vitro regenerated plantlets was also developed. This protocol involved deflasking in vitro plantlets with at least 2 fully-opened healthy leaves and at least 3 roots longer than 1.5 cm, washing the media from the roots with running tap water, planting in 100 mm pots and placing in plastic trays covered with a clear plastic bag in a plant growth chamber. After seven days, the corners of the plastic cover were opened and the bags were completely removed after 10 days. All plantlets were successfully acclimatised regardless of whether 1:1 perlite:potting mix, potting mix, UC mix or vermiculite were used as potting substrates. Parameters were optimised for Agrobacterium-mediated transformation (AMT) of cultivars SA281, 296B and Tx430. The optimal conditions were the use of Agrobacterium strain LBA4404 at an inoculum density of 0.5 OD600nm, heat shock at 43oC for 3 min, use of the surfactant Pluronic F-68 (0.02% w/v) in the inoculation media with a pH of 5.2 and a 3 day co-cultivation period in dark at 22oC. Using these parameters, high frequencies of transient GFP expression was observed in IEs precultured on callus initiation media for 1-7 days as well as in four weeks old IE- and IF-derived callus. Cultivar SA281 appeared very sensitive to Agrobacterium since all tissue turned necrotic within two weeks post-exposure. For cultivar 296B, GFP expression was observed up to 20 days post co-cultivation but no stably transformed plants were regenerated. Using cultivar Tx430, GFP was expressed for up to 50 days post co-cultivation. Although no stably transformed plants of this cultivar were regenerated, this was most likely due to the use of unsuitable regeneration media. Parameters were optimised for transformation by particle bombardment (PB) of cultivars SA281, 296B and Tx430. The optimal conditions were use of 3-7 days old IEs and 4 weeks old IF callus, 4 hour pre- and post-bombardment osmoticum treatment, use of 0.6 µm gold microparticles, helium pressure of 1500 kPa and target distance of 15 cm. Using these parameters for PB, transient GFP expression was observed for up to 14, 30 and 50 days for cultivars SA281, 296B and Tx430, respectively. Further, the use of PB resulted in less tissue necrosis compared to AMT for the respective cultivars. Despite the presence of transient GFP expression, no stably transformed plants were regenerated. The establishment of regenerable ECLs and the optimization of AMT and PB parameters in this study provides a platform for future efforts to develop an efficient transformation protocol for sorghum. The development of GM sorghum will be an important step towards improving its agronomic properties as well as its exploitation for biofuel production.

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Bats (Mammalia: Chiroptera) are among the most successful mammals and likely display the widest range of mating systems within the Class. One mating system that is underrepresented in the Chiroptera is lek breeding, which is characterized by aggregations of sexually displaying males that are visited by receptive females who appraise male displays and actively choose mates, yet receive no direct benefits such as assistance in parenting. Leks are thought to form when males can defend neither resources nor females, making it more economical to establish small breeding territories and self-advertise through sexual displays. Lekking is rare in mammals, and it has been suggested that a lack in the mobility required by females to economically seek out aggregations of sexually displaying males may explain this rarity. Bats, like birds, do not suffer reduced mobility and yet out of over a thousand described species, only one has been confirmed to breed in leks. We examine the rarity of lekking in bats by providing an overview on the current state of knowledge of their mating systems and discuss the ecological and social determinants for the observed trends, contrasted with the prerequisites of lek-breeding behaviour. We use the breeding behaviour of New Zealand's lesser short-tailed bat Mystacina tuberculata, which is believed to be a lek breeder, as a case study for the examination of potential lekking behaviour in bats, and highlight the importance of such research for the development of effective conservation strategies.

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Males of lek-breeding species defend clustered territories from which they display to visiting females. However, the mechanisms leading to the adoption of clustered male display sites are often unknown. In this study, we examined the possibility of a resource-based lek in New Zealand’s lesser short-tailed bat (Mystacina tuberculata) (Mammalia: Chiroptera), by assessing the placement of “singing roosts” used by males in relation to communal roosting sites used by females. The “resource-based lek” model posits that males settle near resources required by females to increase female encounter rates. For most bat species, where females are highly mobile and widely dispersed across landscapes while foraging, communal daytime roosts dominated by females may represent such a resource. Through use of video footage, spatial analyses of singing-roost locations, and passive-integrated transponder tags we confirmed that M. tuberculata employs a lek mating system. We found that male singing roosts were significantly clustered in space, were defended by resident individuals, and were visited by females (who did not receive resources from males) for mating purposes. Transponder records also indicated that some singing roosts were shared between multiple males. Spatial logistic regression indicated that singing-roost locations were associated with communal roosting sites. Communal roosts are selected based on criteria independent of the locations of singing roosts, suggesting that males responded to the location of communal roosts and not the reverse. Mystacina tuberculata thus provides evidence of a resource-based lek, and is only the second bat species worldwide confirmed to use a lek-mating system.

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In order to develop an efficient and reliable biolistics transformation system for pineapples parameters need to be optimised for growth, survival and development of explants pre- and post transformation. We have optimised in vitro conditions for culture media for the various stages of plant and callus initiation and development, and for effective selection of putative transgenic material. Shoot multiplication and proliferation is best on medium containing MS basic nutrients and vitamins with the addition of 0.1 mg/L myo-inositol, 20 g/L sucrose, 2.5 mg/L BAP and 3 g/L Phytagel, followed by transfer to basic MS medium for further development. Callus production on leaf base explants is best on MS nutrients and vitamins, to which 10 mg/L of BAP and NAA each was added. Optimum explant age for bombardment is 17-35 week old callus, while a pre-bombardment osmoticum treatment in the medium is not required. By comparing several antibiotics as selective agent, it has been established that a two-step selection of 2 fortnightly sub-cultures on 50 μg/mL of geneticin in the culture medium, followed by monthly sub-cultures on 100 μg/mL geneticin is optimal for survival of transgenic callus. Shoot regeneration from callus cultures is optimal on medium containing MS nutrients and vitamins, 5% coconut water and 400 mg/L casein hydrolysate. Plants can be readily regenerated and multiplied from transgenic callus through organogenesis. Rooting of shoots does not require any additional plant hormones to the medium. A transformation efficiency of 1 – 3.5% can be achieved, depending on the gene construct applied.

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There is substantial variation in bull breeding soundness evaluation procedures and reports in Australia; the situation is compounded by difficulties in interpretation and the validity of many reports. In an effort to overcome this, the scientific literature was reviewed [Fordyce G. In: Fordyce G, editor. Bull fertility: selection and management in Australia. Eight Mile Plains, Australia: Australian Cattle Vets; 2002] and the needs of stakeholders were considered in preparing a manual, Evaluating and Reporting Bull Fertility [Entwistle KW, Fordyce G. Evaluating and reporting bull fertility. Eight Mile Plains, Australia: Australian Cattle Vets; 2003.] that outlined standards for assessing and reporting bull breeding soundness. A new recording and reporting system, called Bull Reporter, is based on standards from this manual and groups bull fertility traits into five summary categories: Scrotum, Physical, Crush-side Semen, Sperm Morphology, and Serving. The client will generally select which categories they wish to have included in the evaluation to suit their specific purposes. While there is adequate room for comments, the veterinarian is not required to make an overall judgment of whether the bull has normal capacity to sire calves under natural mating management, but ensures the standards for each selected category are met. Professional, standardised, easy-to-read reports are produced either electronically [Entwistle KW, Fordyce G. Evaluating and reporting bull fertility. Eight Mile Plains, Australia: Australian Cattle Vets; 2003.] or manually. A bull owner or their agent signs the certificate to affirm that bulls have not undergone procedures to rectify faults which may have otherwise caused them to fail the standards. An accreditation system for assessing sperm morphology was established because of its demonstrated relationship with pregnancy rates and because of the difficulties in achieving consistent and accurate assessments among laboratories. It is considered that Bull Reporter is applicable to beef and dairy bulls across all levels of management, genotypes and environments throughout Australia, with substantial potential for application elsewhere in the world.

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Water availability is a major limiting factor for wheat (Triticum aestivum L.) in rain-fed agricultural systems worldwide. Root architecture has important functional implications for the timing and extent of soil water extraction, yet selection for root traits in wheat breeding programs has been largely limited due to the lack of suitable phenotyping methods. The aim of this research was to develop a low-cost high-throughput phenotyping method to facilitate selection for desirable root traits. We developed a method to assess ‘seminal root angle’ and ‘seminal root number’ in seedlings – two proxy traits associated to root architecture of mature wheat plants (1). The method involves measuring the angle between the first pair of seminal roots and the number of roots of wheat seedlings grown in transparent pots (Figure 1). Images captured at 5 to 10 days after sowing are analyzed to calculate seminal root angle and number. Performing this technique under “speed breeding” conditions (plants grown at a density of 600 plants / m2, under controlled temperature and constant light) allows the selection based on the desired root traits of up to 5 consecutive generations within 12 months. Alternatively, when focusing only on germplasm screening, up to 52 successive phenotypic assays can be conducted within 12 months. This approach has been shown to be highly reproducible, it requires little resource (time, space, and labour) and can be used to rapidly enrich breeding populations with desirable alleles for narrow root angle and a high number of seminal roots to indirectly target the selection of deeper root system with higher branching at depth. Such root characteristics are highly desirable in wheat to cope with the climate model projections, especially in summer rainfall dominant regions including some Australian, Indian, South American and African cropping regions, where winter crops mainly rely on deep stored water.

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Temperatures have increased and in-crop rainfall decreased over recent decades in many parts of the Australian wheat cropping region. With these trends set to continue or intensify, improving crop adaptation in the face of climate change is particularly urgent in this, already drought-prone, cropping region. Importantly, improved performance under water-limitation must be achieved while retaining yield potential during more favourable seasons. A multi-trait-based approach to improve wheat yield and yield stability in the face of water-limitation and heat has been instigated in northern Australia using novel phenotyping techniques and a nested association mapping (NAM) approach. An innovative laboratory technique allows rapid root trait screening of hundreds of lines. Using soil grown seedlings, the method offers significant advantages over many other lab-based techniques. Another recently developed method allows novel stay-green traits to be quantified objectively for hundreds of genotypes in standard field trial plots. Field trials in multiple locations and seasons allow evaluation of targeted trait values and identification of superior germplasm. Traits, including yield and yield components are measured for hundreds of NAM lines in rain fed environments under various levels of water-limitation. To rapidly generate lines of interest, the University of Queensland “speed breeding” method is being employed, allowing up to 7 plant generations per annum. A NAM population of over 1000 wheat recombinant inbred lines has been progressed to the F5 generation within 18 months. Genotyping the NAM lines with the genome-wide DArTseq molecular marker system provides up to 40,000 markers. They are now being used for association mapping to validate QTL previously identified in bi-parental populations and to identify novel QTL for stay-green and root traits. We believe that combining the latest techniques in physiology, phenotyping, genetics and breeding will increase genetic progress toward improved adaptation to water-limited environments.