Breeding efforts to mitigate damage by heat stress to spikelet sterility and grain quality

Global warming is predicted to aggravate the risk of unstable crop production. It is of great concern that damage to rice spikelet sterility and grain quality will increase, resulting in yield and economic losses. To secure the global food supply and farmers’ income, the development of rice cultivars with heat resilience is a pressing concern. Regarding spikelet sterility, rice cultivars with heat tolerance at different growth stages have been identified in recent years. The early-morning flowering (EMF) trait is effective in heat escape because it shifts the time of day of flowering to earlier in the morning when it is cooler. Although varietal differences are very small, there are some genetic resources for EMF in wild rice accessions. Regarding heat-induced grain chalkiness, heat-tolerant japonica cultivars for mitigating white-back type of chalky grains (WBCG) were found. Quantitative trait loci for heat tolerance at flowering, EMF, and for WBCG in grain quality have been mapped on the rice chromosomes. Further genetic efforts have been successfully connected to the development of near-isogenic lines for each trait with tagged molecular markers. These breeding materials are quite unique and useful in facilitating marker-assisted breeding toward the development of heat-resilient rice in terms of spikelet sterility and grain quality.     

Identification of a peptide in enzymatic hydrolyzate of cheese that inhibits ovalbumin permeation in Caco-2 cells

Because the first step in the triggering of food allergy is the permeation of the allergen through the intestine, enhancement of the intestinal barrier function is thought to be effective for preventing food allergy. In this study, a peptide that inhibits ovalbumin (OVA) permeation in an in vitro Caco-2 cell model was isolated from enzymatic hydrolyzate of cheese (EHC). Amino acid sequence analysis identified the active peptide as GPIVLNPWDQ, a sequence identical to amino acids 102-111 of alphas2-casein. The decapeptide significantly inhibited OVA permeation at a concentration of 10(-6) M. In addition, it was found that a pentapeptide half, NPWDQ, is essential for the inhibitory activity because NPWDQ but not GPIVL had nearly the same inhibitory activity as GPIVLNPWDQ. The possibility exists that EHC and/or peptides possessing the NPWDQ sequence can be practically applied to the prevention of food allergy.     

Footpad reaction induced by Neospora caninum tachyzoite extract in infected BALB/c mice

Little information is available regarding a delayed type hypersensitivity (DTH) reaction in neosporosis. In this study, we examined the elicitation of a DTH reaction in mice infected with Neospora caninum by inoculation of the footpad with tachyzoite antigens. The footpads of BALB/c mice infected with N. caninum and those of non-infected were injected with either the tachyzoite extract, or paraformaldehyde-fixed tachyzoites. In mice inoculated with N. caninum antigens on day 7 p.i. swelling peaked at 6h after injection of the tachyzoite extract. In mice inoculated on days 14, 28 and 56, swelling was observed between 6 and 72 h afterwards. Mice immunized with the tachyzoite extract plus adjuvant showed peak footpad swelling at 6h post injection, and the swelling had decreased at 24h or later. In contrast, mice injected before infection showed no specific swelling. In sections of footpads injected with the tachyzoite extract, exudate had accumulated at 6h post injection and clusters of infiltrated lymphocytes were observed at 48 h post injection. In mice administered anti-CD4+ cell monoclonal antibodies swelling had decreased at 24h post injection of the extract. These results indicate that mice infected with N. caninum produce a DTH reaction, which is a good indicator of the development of type 1 immune responses.     

Survival of ovarian somatic cells during sex change in the protogynous wrasse, Halichoeres trimaculatus

The three-spot wrasse (Halichoeres trimaculatus), which inhabits the coral reefs of Okinawa, changes sex from female to male. Sex change in this species is controlled by a social system. Oocytes disappear completely from the ovary, and male germ cells and somatic cells comprising testicular tissue arise a new during the sex change process. However, little is known of the fate and origin of the gonadal tissue-forming cells during sex change. In particular, the fate of ovarian somatic cells has not been determined, although the ovarian tissue regresses histologically. To approach this question, we analyzed apoptosis and cell proliferation in the sex-changing gonads. Unexpectedly, we found that few apoptotic somatic cells were present during sex change, suggesting that ovarian somatic cells might survive during the regression of the ovarian tissue. On the other hand, cell proliferation was detected in many granulosa cells surrounding the degenerating oocytes, a few epithelial cells covering ovigerous lamella and a few somatic cells associated with gonial germ cells at an early stage of sex change. Then, we found that proliferative ovarian somatic cells remained in the gonads late in the sex change process. Based on these results, we concluded that some functional somatic cells of the ovary are reused as testicular somatic cells during the gonadal sex change in the three-spot wrasse.     

FACE条件下O3浓度增高对小麦产量和籽粒充实的影响

 【目的】探讨近地层大气O3浓度增高对小麦生产的影响。【方法】2007—2009年度应用FACE研究平台,以O3自然浓度(A-O3)为对照,设计O3浓度增高50% (E-O3)进行对比试验,采用烟农19、扬麦16、嘉兴002、扬麦15和扬辐麦2号等5个品种为对象,研究大气O3浓度增高50%对不同基因型小麦品种籽粒产量及其构成因素的影响。【结果】O3浓度增高显著降低小麦籽粒产量,降幅为10.10%—34.51%,平均为19.74%,品种、年度间存在显著或极显著差异。O3浓度增高条件下千粒重降低17.88%(10.16%—29.47%);每穗粒数下降3.47%(-1.53%—11.90%),但穗数平均较对照增加0.95%(-14.58%—23.74%),处理、品种和年度间存在显著或极显著差异。O3浓度增高50%使籽粒长、宽、厚和籽粒体积分别减小0—4.16%、7.95%—20.24%、2.66%—11.00%和8.5%—31.5%;皱缩指数增大0.23%—36.66%,籽粒灌浆速率降低,籽粒充实度变化为-21.40%—3.76%,最终导致粒重降低。【结论】FACE条件下O3浓度增高使籽粒灌浆物质来源不足,籽粒库容变小,充实度降低,粒重变小,最终导致小麦籽粒产量下降。