Confirmation of Novel Quantitative Trait Loci for Seed Dormancy at Different Ripening Stages in Rice

Seed dormancy contributes resistance to pre-harvest sprouting.Effects on respective quantitative trait loci (QTLs) for dormancy should be assessed by using fresh seeds before germinability altered through storage.We investigated QTLs related to seed dormancy using backcross inbred lines derived from a cross between Nipponbare and Kasalath.Four putative QTLs for seed dormancy were detected immediately after harvest using composite interval mapping.These putative QTLs were mapped near C1488 on chromosome 3 (qSD-3.1),R2171 on chromosome 6 (qSD-6.1),R1245 on chromosome 7 (qSD-7.1) and C488 on chromosome 10 (qSD-10.1).Kasalath alleles promoted dormancy for qSD-3.1,qSD-6.1 and qSD-7.1,and the respective proportions of phenotypic variation explained by each QTL were 12.9%,9.3% and 8.1%.We evaluated the seed dormancy harvested at different ripening stages during seed development using chromosome segment substitution lines (CSSLs) to confirm gene effects.The germination rates of CSSL27 and CSSL28 substituted with the region including qSD-6.1 were significantly lower than those of Nipponbare and other CSSLs at the late ripening stage.Therefore,qSD-6.1 is considered the most effective novel QTL for pre-harvest sprouting resistance among the QTLs detected in this study.     

Habitat Selection and Breeding Success in a Forest-nesting Alcid, the Marbled Murrelet, in Two Landscapes with Different Degrees of Forest Fragmentation

We studied habitat selection and breeding success in marked populations of a protected seabird (family Alcidae), the marbled murrelet (Brachyramphus marmoratus), in a relatively intact and a heavily logged old-growth forest landscape in south-western Canada. Murrelets used old-growth fragments either proportionately to their size frequency distribution (intact) or they tended to nest in disproportionately smaller fragments (logged). Multiple regression modelling showed that murrelet distribution could be explained by proximity of nests to landscape features producing biotic and abiotic edge effects. Streams, steeper slopes and lower elevations were selected in both landscapes, probably due to good nesting habitat conditions and easier access to nest sites. In the logged landscape, the murrelets nested closer to recent clearcuts than would be expected. Proximity to the ocean was favoured in the intact area. The models of habitat selection had satisfactory discriminatory ability in both landscapes. Breeding success (probability of nest survival to the middle of the chick rearing period), inferred from nest attendance patterns by radio-tagged parents, was modelled in the logged landscape. Survivorship was greater in areas with recent clearcuts and lower in areas with much regrowth, i.e. it was positively correlated with recent habitat fragmentation. We conclude that marbled murrelets can successfully breed in old-growth forests fragmented by logging.     

Effect of monensin withdrawal on rumen fermentation,methanogenesis and microbial populations in cattle

This study was designed to obtain information on the residual influence of dietary monensin on ruminant fermentation, methanogenesis and bacterial population. Three ruminally cannulated crossbreed heifers (14 months old, 363 ± 11 kg) were fed Italian ryegrass straw and concentrate supplemented with monensin for 21 days before sampling. Rumen fluid samples were collected for analysis of short chain fatty acid (SCFA) profiles, monensin concentration, methanogens and rumen bacterial density. Post‐feeding rumen fluid was also collected to determine in vitro gas production. Monensin was eliminated from the rumen fluid within 3 days. The composition of SCFA varied after elimination of monensin, while total production of SCFA was 1.78 times higher than on the first day. Methane production increased 7 days after monensin administration ceased, whereas hydrogen production decreased. The methanogens and rumen bacterial copy numbers were unaffected by the withdrawal of monensin.     

Humeral Chondrosarcoma in a Hokkaido Brown Bear (Ursus arctos yesoensis)

Humeral chondrosarcoma was found in an 18-year-old male Hokkaido brown bear (Ursus arctos yesoensis). Necropsy revealed a large firm mass under the left superficial pectoral muscle at the axillary region. The mass involved the left shoulder joint and peripheral muscles, and connected to the head of the humerus with osteolysis. Histopathologically, the mass was composed of irregularly shaped myxomatous to cartilaginous tumor lobules. The tumor cell showed moderate nuclear atypia with a relatively high mitotic index, especially in the edges of the myxomatous lobules. The tumor cells were positively immunostained with vimentin and S-100 protein. Based on these findings, the tumors were diagnosed as chondrosarcoma. Metastases were found in the left axillary lymph node, lungs, liver and kidney.     

Relationship between the first ovulation within three weeks postpartum and subsequent ovarian cycles and fertility in high producing dairy cows

The aim of this study was to investigate the relationship between the first ovulation within 3 weeks postpartum and subsequent ovarian cycles and fertility in high producing dairy cattle in Hokkaido, Japan. In Experiment 1, 110 cows (44 primiparous and 66 multiparous) were used to determine the effects of the first ovulation within 3 weeks postpartum on subsequent ovarian cycles. Milk samples were collected twice weekly from 7 to 100 days postpartum. The first ovulation was identified by an increase in milk progesterone (P4) to more than 1 ng/ml within 3 weeks postpartum. The numbers of cows showing ovulation and anovulation within 3 weeks postpartum were 31 (70.5%) and 13 (29.5%) in the primiparous cows and 35 (53.0%) and 31 (47.0%) in the multiparous cows, respectively. The patterns of ovarian resumption after calving were classified into two types (normal ovarian cycles and abnormal ovarian cycles) on the basis of milk P4 concentrations. Initiation of normal ovarian function in cows ovulated within 3 weeks postpartum occurred earlier than in anovulated cows regardless of the number of calvings (primiparous, 27.8 days vs. 44.4 days; multiparous, 30.6 days vs. 55.7 days; P<0.01). Out of the multiparous cows that ovulated within 3 weeks postpartum, initiation of normal ovarian function followed by a normal luteal phase was earlier than when it was followed by an abnormal luteal phase (25.5 days vs. 40.4 days; P<0.05). Milk P4 concentrations after the first ovulation were lower than those after the second ovulation in both the primiparous and multiparous cows (P<0.05). In Experiment 2, 22 multiparous cows were used to determine the effects of the first ovulation within 3 weeks postpartum on subsequent fertility. Blood samples were collected once a week from 0 to 3 weeks postpartum. The interval from parturition to first service in ovulated cows was shorter than in anovulated cows (68.4 days vs. 94.8 days; P<0.05). The conception rate by 100 days after calving tended to be higher in ovulated cows than in anovulated cows (50.0% vs. 16.7%, P=0.09). In conclusion, our data strongly suggests that ovulation within 3 weeks postpartum is a crucial phenomenon for subsequent resumption of ovarian function and conception, and thus it can be used as an index of subsequent reproductive performance.     

Polymorphism in promoter region of growth hormone receptor is associated with potential production capacity of insulin‐like growth factor‐1 in pre‐pubertal Holstein heifers

Insulin‐like growth factor‐1 (IGF‐1) is one of the important factors for growth, milk production and reproductive functions and mainly released from the liver in response to growth hormone (GH) via GH receptor (GHR) in cattle. Recently, some single nucleotide polymorphisms (SNPs) were identified in the bovine GHR gene. Some GHR‐SNPs were shown to be related to plasma IGF‐1 concentration in cattle. Hence, the capacity to IGF‐1 production in the liver might be affected by GHR‐SNP and associated with performance in the future. This study examined whether GHR‐SNP is associated with IGF‐1 production in the liver of pre‐pubertal heifers. In 71 Holstein calves, blood samples for genomic DNA extraction were obtained immediately after birth. To genotype the GHR‐SNPs in the promoter region, polymerase chain reaction (PCR) products were digested with restriction enzyme NsiI (cutting sites: AA, AG and GG). All heifers at 4 months of age were intramuscularly injected with 0.4 mg oestradiol benzoate. Blood samples were obtained from the jugular vein just before (0 h) and 24 h after injection. The number of AA, AG and GG at the NsiI site was 0, 17 and 54 respectively. In AG and GG, plasma GH concentrations were higher pre‐injection than 24 h post‐injection (p < 0.01). Moreover, plasma GH concentrations in AG post‐injection were higher than in GG (p < 0.05). In contrast, the GG genotype exhibited higher plasma IGF‐1 concentrations in pre‐injection than post‐injection (p < 0.01), although oestradiol did not change IGF‐1 concentration in the AG genotype. We conclude that the GG polymorphism in the promoter region of GHR is associated with a higher potential capacity of IGF‐1 production in the liver of cattle.     

Leucocyte profile and growth rates as indicators of crowding stress in pejerrey fingerlings (Odontesthes bonariensis)

Crowding is one of the most common stressors found in intensive aquaculture, compromising growth rates and immune function. Plasmatic cortisol is a classic stress biomarker for fish, but its quantification is expensive and demands blood volumes that small individuals do not provide, constraining the usage of this technique to assess stress in fingerlings. The leucocyte profile is an alternative methodology to quantify stress with reduced costs and volumes of blood. Stress conditions promote neutrophilia and lymphocytopenia as response to elevated glucocorticoids levels. Considering the difficulties to assess stress imposed by intensive fish farming using measurement of glucocorticoid hormones, this study aimed to evaluate the stress‐induced changes in leucocyte profiles and growth rates imposed by crowding in fingerlings of Odontesthes bonariensis, a promising South‐American candidate for freshwater aquaculture. To meet these objectives, fingerlings (initial weight 0.05 ± 0.06 g and length 1.68 ± 0.13 cm) were reared for 45 days under three rearing densities (1, 5 and 10 fingerlings L^?1). At the end of this period, fish were anaesthetized and euthanized to obtain the leucocyte profile, neutrophil:lymphocyte ratio (N:L) and growth rate. Increasing density promoted: significant reduction in growth (final length, weight and specific growth rate); neutrophilia and lymphocytopenia; and increased N:L ratio. Concluding, the tested rearing densities imposed distinct levels of stress characterized by different N:L ratio, demonstrating that the leucocyte profile is a reliable alternative to measure stress levels in O. bonariensis fingerlings and probably in other fish species.     

Eastern little tuna,Euthynnus affinis (Cantor, 1849) mature and reproduce within 1 year of rearing in land‐based tanks

Eastern little tuna (ELT, Euthynnus affinis) is expected to see use as a novel aquaculture species due to its rapid growth and high economic value. In this study, closing of the complete life cycle of ELT in land‐based tanks was successfully carried out. Seed production of a first generation (F1) derived from wild‐caught ELT broodstock was conducted in 2010, 2011 and 2012. Survival percentages of F1 ELT at 365 days post hatching for the 2010, 2011 and 2012 year classes were 0.9%, 0.4% and 6.3% respectively. On average, F1 ELT were approximately 40 cm in total length and weighed 1500 g by the time they reached 1 year of age. Successful artificial induction of spawning was achieved in 1‐year‐old F1 ELT using a gonadotropin‐releasing hormone analogue (GnRHa). Induction of spawning was successful at the first administration of GnRHa in the 2010, 2011 and 2012 year classes. First spawning was observed at 4 or 5 days post implantation, which indicated that oogenesis and spermatogenesis progressed within 1 year of rearing in land‐based tanks. During spawning periods, the average number of fertilized eggs and the average number of hatched larvae per spawning event in the 2010, 2011 and 2012 year classes were 20,480 eggs day^?1 and 177 larvae day^?1, 39,423 eggs day^?1 and 9347 larvae day^?1, and 819,555 eggs day^?1 and 674,445 larvae day^?1 respectively. Therefore, it was concluded that both male and female ELT reared in land‐based tanks were capable of reproduction at 1 year of age.