Yields of cultured Pacific oysters Crassostrea gigas Thunberg improved after one generation of selection

Parental families (G₀) in three lines of Pacific oysters were selected based on live weight and meat yields at harvest. The average live weight yield of progeny (G₁) from crossing G₀-selected lines in seven trials was 9.5% greater than that of nonselected control families and live weight yields were significantly greater (ANOVA, P<0.001) in four out of seven trials. The response to selection was greater if G₁ families were tested at the same site as their parents' selection site rather than at a different site, although this effect was only significant for G₁ families of cohort 5 (P<0.01) but not cohort 7 (P>0.05). A significant genotype×environment interaction affected yields in both cohort 5 and cohort 7 (ANOVA; P<0.001). In addition, correlation between the yields of the same families planted at both intertidal and subtidal sites was positive but weak (cohort 5, r=0.30; cohort 7, r=0.35), indicating that selection for high yield in one environment would likely result in a low correlated response in a different environment. Nonetheless, it was possible to identify six families in cohort 5 and four families in cohort 7 that were among the top 10 families at both sites. Further evaluation of families across a wider range of environments is needed to determine if it is possible to substantially improve yields by selecting “generalist” families that perform well along the whole Pacific coast, or whether it will be necessary to select lines that are suited to particular sites.     

Use of ultrasonic Doppler waveforms to estimate changes in uterine artery blood flow and vessel compliance

Previous data from our laboratory have demonstrated that uterine blood flow (UBF) and uterine arterial smooth muscle tone vary regularly during the estrous cycle of the cow. Uterine blood flow is highest and uterine arterial tone is lowest at estrus, whereas UBF is lowest and uterine arterial tone is highest during the luteal phase of the cycle. Blood flow through arteries is highly pulsatile; changes in arterial wall properties affect shape of the velocity waveform. This study was conducted to evaluate changes in uterine arterial velocity waveforms throughout the estrous cycle of the cow and to relate these changes to fluctuations in UBF and concentrations of estrogen and(or) progesterone in systemic blood. Pulsatile velocity waveforms were obtained daily from pulsed-wave ultrasonic probes placed surgically on the middle uterine artery of five beef cows exhibiting estrous cycles of normal duration (d 0 = day of estrus). Velocity waveforms varied regularly during the estrous cycle of each cow in association with changes in UBF and steroid concentrations. Further, two distinct velocity waveform shapes were observed during the estrous cycle. The first waveform shape, which was observed during periods of high UBF (d -4 to +4 of the estrous cycle), was characteristic of a highly compliant vessel and was associated with a high estrogen:progesterone ratio. The second waveform shape, which was observed from d 7 to 14 of the estrous cycle, was characteristic of a less compliant vessel and was associated with a depressed estrogen:progesterone ratio. These data suggest that compliance of the uterine artery changes during the estrous cycle in association with the changing estrogen:progesterone ratio in blood.     

Interval to first postweaning estrus and causes for leaving the breeding herd in Large White, Landrace, Yorkshire and Chester White females after three parities

Three hundred and five Large White (LW, 93), Landrace (L, 92), Yorkshire (Y, 69) and Chester White (CW, 51) gilts produced at the Roman L. Hruska U.S. Meat Animal Research Center over 3 yr with 15 to 41 gilts per breed group per year were housed in total confinement and mated to farrow at 1 yr of age. After 28 to 30 d lactation, piglets were weaned and all females were observed for estrus daily for 30 d. During the year that each gilt initially farrowed, she was mated to produce a second and third litter if she returned to estrus within 30 d after piglet removal. Interval from weaning (d 0) to estrus and reason for leaving the breeding herd were recorded for each animal. Interval from weaning to estrus was influenced by breed (P less than .01), parity (P less than .01) and interaction between breed and parity (P less than .01). Intervals from weaning to estrus, in first parity females which exhibited estrus, were 7.8, 6.6, 9.3 and 14.0 d for the LW, L, Y and CW breeds. Intervals for all females after the second litter were 6.8, 4.9, 8.0 and 9.1 d, and after the third litter 6.4, 5.2, 8.3 and 10.1 d for the LW, L, Y and CW breeds. Breed, parity and year (P less than .01) affected the number of females not exhibiting estrus. Percentages of females not exhibiting estrus were 6.5, 18.7, 37.7 and 23.5 for the LW, L, Y and CW breeds and 16.1, 2.3 and 2.0 for sows after the first, second and third parities.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ileocecal intussusception in horses: 26 cases (1981-1988)

The case records of 26 horses with ileocecal intussusception over a 7-year period were reviewed to determine clinical features of the disease and response to treatment. The median age of horses with ileocecal intussusception was 1 year and ranged from 2 weeks to 19 years. There was no apparent gender or breed predisposition to this disease. An acute form of ileocecal intussusception was diagnosed in 19 horses with signs of moderate to severe abdominal pain of less than or equal to 24 hours' duration, and a chronic form was diagnosed in 7 horses with signs of intermittent, mild to moderate abdominal pain of more than 3 days' duration. Horses with chronic ileocecal intussusception had a history of weight loss or failure to gain weight, slow growth, poor appetite, low-grade pyrexia, and postprandial signs of abdominal pain. At surgery, the involved segments of intestine (intussusceptum and intussuscipiens) in chronic cases were 2 to 10 cm long, and the ileum and much of the distal portion of the jejunum were flaccid, dilated, and thick walled. In the acute cases, the length of involved intestine ranged from 6 to 457 cm. Whereas only 1 of 7 chronic intussusceptions (14%) could be reduced, 9 of 19 (47%) acute intussusceptions were reducible. Surgical treatment included resection and jejunocecostomy (6 horses), partial resection through a cecotomy and a side-to-side jejunocecostomy (2 horses), and a side-to-side ileocecostomy or jejunocecostomy without resection (12 horses, 7 of which had chronic intussusception). Six horses with acute intussusception were euthanatized before or during surgery.(ABSTRACT TRUNCATED AT 250 WORDS)     

Leucine stimulates mammalian target of rapamycin signaling in C2C12 myoblasts in part through inhibition of adenosine monophosphate-activated protein kinase

Mammalian target of rapamycin (mTOR) signaling is one of the main signaling pathways controlling protein synthesis. Leucine treatment upregulates mTOR signaling, which enhances protein synthesis; however, the mechanisms are not well understood. Herein, treatment of C2C12 myoblast cells with leucine enhanced the phosphorylation of mTOR and ribosomal protein S6 kinase. Leucine treatment also decreased the adenosine monophosphate/ATP ratio in myoblasts by 36.4 +/- 9.1% (P < 0.05) and reduced the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) alpha subunit at Thr172 (28.6 +/- 4.9% reduction, P < 0.05) and inhibited AMPK activity (43.6 +/- 3.5% reduction, P < 0.05). In addition, leucine increased the phosphorylation of mTOR at Ser2448 by 63.5 +/- 10.0% (P < 0.05) and protein synthesis by 30.6 +/- 6.1% (P < 0.05). Applying 5-aminoimidazole-4-carbox-amide 1-beta-d-ribonucleoside, an activator of AMPK, abolished the stimulation of mTOR signaling by leucine, showing that AMPK negatively controls mTOR signaling. To further show the role of AMPK in mTOR signaling, myoblasts expressing a dominant negative AMPKalpha subunit were employed. Negative myoblasts had very low AMPK activity. The activation of mTOR induced by leucine in these cells was abated, showing that AMPK contributed to mTOR activation. In conclusion, leucine stimulates mTOR signaling in part through AMPK inhibition. This study implicates AMPK as an important target for nutritional management to enhance mTOR signaling and protein synthesis in muscle cells, thereby increasing muscle growth.     

QTL mapping of resistance in lentil (Lens culinaris ssp. culinaris) to ascochyta blight (Ascochyta lentis)

Quantitative trait locus (QTL) analysis of ascochyta blight resistance in lentil was conducted using genomic maps developed from two F₂ populations, viz. ILL5588/ILL7537 and ILL7537/ILL6002. Five QTLs for ascochyta blight resistance were identified by composite interval mapping (CIM) across four linkage groups (LG) in population ILL5588/ILL7537. Three QTLs were identified by CIM in population ILL7537/ILL6002 (two in close proximity on LGI and one on LGII). Two of these coincided with regions identified using multiple interval mapping (MIM) and were shown to be conditioned by dominant and partial dominant gene action. Together, they accounted for approximately 50% of the phenotypic variance of disease severity. Comparison between the two populations revealed a potentially common QTL and several common regions that contained markers significantly associated with resistance. This study demonstrated the transferability of QTLs among populations and identified markers closely linked to the major QTL that may be useful for future marker‐assisted selection for disease resistance.     

Application of biotechnology in breeding lentil for resistance to biotic and abiotic stress

Summary Lentil is a self-pollinating diploid (2n = 14 chromosomes) annual cool season legume crop that is produced throughout the world and is highly valued as a high protein food. Several abiotic stresses are important to lentil yields world wide and include drought, heat, salt susceptibility and iron deficiency. The biotic stresses are numerous and include: susceptibility to Ascochyta blight, caused by Ascochyta lentis; Anthracnose, caused by Colletotrichum truncatum; Fusarium wilt, caused by Fusarium oxysporum; Sclerotinia white mold, caused by Sclerotinia sclerotiorum; rust, caused by Uromyces fabae; and numerous aphid transmitted viruses. Lentil is also highly susceptible to several species of Orabanche prevalent in the Mediterranean region, for which there does not appear to be much resistance in the germplasm. Plant breeders and geneticists have addressed these stresses by identifying resistant/tolerant germplasm, determining the genetics involved and the genetic map positions of the resistant genes. To this end progress has been made in mapping the lentil genome and several genetic maps are available that eventually will lead to the development of a consensus map for lentil. Marker density has been limited in the published genetic maps and there is a distinct lack of co-dominant markers that would facilitate comparisons of the available genetic maps and efficient identification of markers closely linked to genes of interest. Molecular breeding of lentil for disease resistance genes using marker assisted selection, particularly for resistance to Ascochyta blight and Anthracnose, is underway in Australia and Canada and promising results have been obtained. Comparative genomics and synteny analyses with closely related legumes promises to further advance the knowledge of the lentil genome and provide lentil breeders with additional genes and selectable markers for use in marker assisted selection. Genomic tools such as macro and micro arrays, reverse genetics and genetic transformation are emerging technologies that may eventually be available for use in lentil crop improvement.