Hyperaccumulation of selenium in hybrid striped bass: a functional food for aquaculture?

One method of increasing the value of aquacultured product is to produce fillets that are fortified with minerals that are beneficial to human health – that is enhance the functionality of an already healthy product. A good candidate mineral in this regard is selenium (Se) which is of vital importance to normal metabolism in humans. In order to evaluate the dose response and tissue accumulation of supplemental dietary Se, a study was undertaken with hybrid striped bass (HSB). Animals were fed diets supplemented with either organic (0–3.2 mg kg^?1 as SelPlex^®) or inorganic (0.2 and 0.4 mg kg^?1 as sodium selenite) Se for 6 weeks. Because basal fishmeal‐based diets contained 1.22 mg Se kg^?1, doses of Se delivered equated to 1.22–4.42 mg kg^?1. At trial end, greatest weight gain was observed in fish receiving 0.2 mg Se kg^?1, irrespective of form (organic/inorganic). Se accumulation in HSB liver and fillet revealed a classical dose‐response once a threshold level of 0.2 mg Se kg^?1 was surpassed. Greatest tissue accumulation of Se was observed in fish fed the 3.2 mg Se kg^?1 level (P > 0.0001). A 100 g portion of Se‐enhanced HSB fillet would contain between 33 and 109 μg Se, amounting to a dietary intake of between 25 and 80 μg Se; a level that would satisfy present daily intake recommendations. Comparison of tissue Se levels indicated that the muscle provides a more conspicuous gauge of dietary Se dose‐response than does liver. Dietary treatments of between 0.4 and 1.6 mg organic Se kg^?1 reduced (P < 0.024) plasma glutathione peroxidase (GSH‐Px) activity. No differences were observed in ceruloplasmin, lysozyme or GSH‐Px activities between organic and inorganic Se when delivered at the 0.2 mg Se kg^?1 level. Ceruloplasmin, lysozyme and GSH‐Px levels were elevated (P ≥ 0.025) in fish fed the diet containing 0.4 mg inorganic Se kg^?1.     

Reproductive season and female maturity size of coconut crab <Emphasis Type="Italic">Birgus latro</Emphasis> on Hatoma Island,southern Japan

Information about reproductive season, size at sexual maturity and size-dependent reproductive potentials is important for efficient resource management. Such information is necessary to determine seasonal closures and minimum legal size limits. To conserve resources of coconut crab Birgus latro, which are in danger of extinction due to excessive exploitation, their reproductive season, female size at functional maturity and relationship between female size and reproductive potentials were investigated. The reproductive season started in early June and ended late August, and females with higher reproductive potentials showed a tendency to spawn early in the reproductive season. The prohibition of exploiting the resources during the reproductive season, especially early in the season, would be appropriate for sustainability of high reproductive outputs. Fifty percent of investigated females matured functionally at 24.5-mm thoracic length (TL). However, the size at which all females reached functional maturity was 32.3 mm TL, and there was a wide variation in the size of functional maturity among individuals. We must determine minimum legal size by taking the variation into account to allow all individuals to mate at least once before they are caught, which may prevent serious depression in reproductive rate and genetic diversity.     

石灰、硅酸钠和羟基磷灰石对烟草吸收镉的影响

为了探讨施用不同钝化剂对烟草吸收富集镉的效果,采用盆栽试验研究了石灰、硅酸钠和羟基磷灰石对Pb-Cd复合污染土壤上的烟草镉吸收富集的影响。结果表明,土壤pH值均随3种钝化剂用量的增大而升高,而土壤有效镉(DTPA-提取)含量则随之降低。土壤有效镉的最大降幅分别为:32 g/kg羟基磷灰石处理(52.4%)16 g/kg石灰处理(37.0%)12.5 g/kg硅酸钠处理(14.1%)。3种钝化剂都降低了烟株各部位镉的含量,其对烟叶镉含量的平均最大降幅分别为87%(16 g/kg石灰处理),74.7%(12.5 g/kg硅酸钠处理)和82.2%(32 g/kg羟基磷灰石处理)。石灰和羟基磷灰石对镉在根-茎之间的转移无显著影响,而硅酸钠则显著降低了镉在根-茎之间的转移。综上,镉污染的植烟土壤可以施用这些钝化剂以降低烟叶中镉的含量。     

Growth and yield responses of upland NERICAs to variable water management under field conditions

This study aimed to investigate the possible causes for inconsistent performances of upland New Rice for Africa (NERICA) varieties in uplands and lowlands, while identifying important determinants in grain yield under deficient soil moisture. We compared the growth and yield of NERICA 1 and NERICA 5 to those of Yumenohatamochi, a Japanese upland variety, and Hinohikari, a Japanese lowland variety, subjected to different water management regimes (continually flooded, supplementary irrigation, and non-irrigation). Under conditions of deficient soil moisture, panicle number per square meter, spikelet number per panicle, and 1000-grain weight of NERICAs decreased, whereas the panicle number of the Japanese varieties experienced little change. In contrast, the grain filling ratio was unaffected by water management, irrespective of variety. The primary source of yield reduction under low soil water conditions was a decrease in spikelet number per panicle, and water stress intensity was the primary factor for the degree of this reduction. Variation in the abortion of secondary rachis-branches caused differences between NERICAs in their spikelet number response to soil moisture deficiency. The inconsistency in NERICA performance across uplands vs. lowlands can be partially attributed to variation in yield response to low soil water conditions. Moreover, water stress intensity and the presence of a water gradient along the vertical soil profile may combine to affect the fluctuation in NERICA performance under upland conditions.     

Polymerisation of gluten proteins in developing wheat grain as affected by desiccation

The breadmaking quality of wheat is affected by the composition of gluten proteins and the polymerisation of subunits that are synthesised and accumulated in developing wheat grain. The biological mechanisms and time course of these events during grain development are documented, but not widely confirmed. Therefore, the aim of this study was to monitor the accumulation of gluten protein subunits and the size distribution of protein aggregates during grain development. The effect of desiccation on the polymerisation of gluten proteins and the functional properties of gluten were also studied. The results showed that the size of glutenin polymers remained consistently low until yellow ripeness (YR), while it increased during grain desiccation after YR. Hence, this polymerisation process was presumed to be initiated by desiccation. A similar polymerisation event was also observed when premature grains were dried artificially. The composition of gluten proteins, the ratios of glutenin to gliadin and high molecular weight-glutenin subunits to low molecular weight-glutenin subunits, in premature grain after artificial desiccation showed close association with the size of glutenin polymers in artificially dried grain. Functional properties of gluten in these samples were also associated with polymer size after artificial desiccation.     

脉冲电流烧结Al2O3颗粒的广义热弹性分析

脉冲电流烧结过程的颈部形成机理,特别是非导电粉末材料,是需要着重研究的核心问题。以非导电Al₂O₃粉末为研究对象,引入L-S（Lord and Shulman）型广义热弹性方程,初步探究烧结初期非导电粉末颈部局部高温形成以及快速烧结机理。利用Comsol Multiphysics模拟得到脉冲电流烧结过程中颗粒内部的温度场和应力场分布以及烧结颈部的化学势和空位浓度变化规律。数值结果表明,热以波的形式在烧结颈部产生叠加,形成局部高温。化学势变化表明：烧结初期表面扩散占主要作用,空位浓度差的突变使烧结颈部产生局部空位浓度梯度,促进烧结颈长过程,缩短烧结时间。     

可食性液态膜复合保鲜剂对番茄保鲜效果的研究

以番茄为试材,通过壳聚糖、可溶性淀粉、羧甲基纤维素钠配制成不同浓度的复合保鲜液浸泡涂膜处理,研究其对番茄保鲜效果的影响。结果表明,复合保鲜液涂膜可有效地降低番茄果实的失重率、腐烂率、可溶性固形物含量,抑制多酚氧化酶活性,维持番茄VC含量,保持番茄果实较好的感官品质,且以0.5%壳聚糖+0.8%可溶性淀粉+0.3%羧甲基纤维素钠复配的复合保鲜液涂膜对番茄有较好的保鲜效果,15℃环境下其货架期延长到15 d以上。     

比格犬胫神经皮层体感诱发电位正常值研究

为了测定比格犬胫神经皮层体感诱发电位(somatosensory evoked potential,SEP)的波形及其潜伏期和波幅的正常值。选用15只健康比格犬,在异氟烷吸入麻醉状态下,使用肌电诱发电位仪电刺激其胫神经,将自制参考电极和记录电极分别放置于头部Fz处和Cz处记录SEP波形。结果表明:15只比格犬刺激左右侧胫神经均可记录到清晰的双向SEP波。刺激左侧胫神经引发的波形潜伏期为P(21.71±1.978)ms、N(32.61±2.568)ms、P-N(10.90±1.338)ms,其变异系数分别为9.11%、7.87%、12.88%;波幅为(2.762±1.230)μV,变异系数为41.47%;刺激右侧胫神经引发的波形潜伏期为P(21.49±1.985)ms、N(32.55±2.359)ms、P-N(11.06±1.153)ms,其变异系数分别为9.24%、7.25%、10.24%;波幅为(2.634±1.092)μV,变异系数为44.55%。潜伏期和波幅左右侧差异均不显著(P0.05)。对正常比格犬胫神经皮层SEP的测定,获得了清晰的SEP波形及各波潜伏期和波幅的正常值,印证了潜伏期的稳定性优于波幅的稳定性,可以为实验室研究犬病理状态下的SEP和宠物临床应用SEP诊断疾病提供参考依据。     

Na2CO3胁迫对非洲凤仙种子萌发及幼苗生长的影响

采用室内水培试验,以不同浓度(10,20,30,40,50,60,70 mmol/L)的Na2CO3对非洲凤仙种子和幼苗进行胁迫处理,测定其种子发芽率、发芽指数、发芽势和叶绿素含量等指标.结果表明:各项指标与Na2CO3胁迫浓度呈明显负相关.当Na2CO3浓度达到50 mmol/L时,发芽率、发芽指数和发芽势显著下降,说明高浓度Na2CO3溶液对种子的萌发具有强烈的抑制作用.Na2CO3胁迫使叶绿素含量显著降低,严重影响幼苗的光合能力,抑制幼苗的正常生长.     

亚硒酸钠浸种对春小麦种子萌发特性的研究

为研究硒浸种对春小麦种子活力和幼苗生长特性的影响,分别设置0,0.5,1.0,2.5,3.5,5.0,10.0,50.0 mg/L共8个亚硒酸钠溶液浓度,通过发芽试验,比较研究了不同浓度的亚硒酸钠浸种对春小麦种子萌发和幼苗生长的影响.结果表明:随着亚硒酸钠溶液浓度升高,春小麦种子的发芽率、发芽势、发芽指数、活力指数、幼苗和根长以及干鲜重等指标均呈先升高后下降的趋势;1.0 mg/L的亚硒酸钠溶液对小麦种子萌发和幼苗生长有促进作用;随着亚硒酸钠浓度的升高(≥2.5 mg/L),其各项指标显著下降,并对根和苗的生长表现出抑制作用;因此在实际生产中,掌握合适的硒浸种浓度非常关键.