Visible transmission spectroscopy for the assessment of egg freshness

The objective of this research was to investigate the feasibility of visible transmission spectroscopy for the non‐destructive assessment of the freshness of an individual egg. A total of 600 intact white‐shelled eggs of the same flock (Lohmann, 40 weeks of age) were measured. To obtain a considerable variation in freshness, groups consisting of 60 eggs were stored (18 °C, 55% RH) for 0, 2, 4, 6, 8, 10, 12, 14, 16 and 18 days. The non‐destructive spectral measurements were compared with the two most widely used destructive freshness parameters, namely Haugh units and albumen pH. A partial least squares (PLS1) model was built in order to predict Haugh units and pH of the albumen based on the transmission spectra. The correlation coefficients between the predicted value and the measured value were 0.842 and 0.867 for Haugh unit and pH of the albumen, respectively. These results show that the light transmission spectrum of an egg provides quantitative information about egg freshness. Relevant information concerning egg freshness is restricted to the interval between 570 and 750 nm. Furthermore, the models obtained for both destructive parameters were strikingly similar, indicating that Haugh unit and pH have the same physico‐chemical background. Copyright © 2006 Society of Chemical Industry     

非洲爪蟾卵提取物中200nm膜泡与环形片层及核被膜上核孔复合体形成的关系

将ＬａｍｂｄａＤＮＡ引入活化的非洲爪蟾卵提取物中，在由磷酸肌酸与磷酸肌酸激酶构成的ＡＴＰ再生系统的参与下，在这种非细胞体系中能够围绕由ＬａｍｂｄａＤＮＡ诱导形成的染色质重建核被膜结构，同时在染色质外出现类似核被膜结构的环形片层。在这两种膜结构中核孔复合体的形成都与直径２００ｎｍ左右的单层圆形小膜泡密切相关，这些小膜泡可以附着在染色质表面或独立于染色质之外相互融合成扁平囊状的双层膜片层，双层膜进一步融合形成核孔，与此同时，核孔复合体在核孔上完成装配。     

Uric Acid: The Sperm-Release Pheromone of the Marine Polychaete Platynereis dumerilii

In the marine polychaete, Platynereis dumerilii, reproductive behavior in the two sexes is synchronized by the consecutive discharge of male and female sex-specific pheromones. After the female releases the eggs into the free water column, immediate fertilization is achieved by several males circling around the eggs emitting sperm clouds. We report the isolation and identification of the sperm-release pheromone present in the coelomic fluid of sexually mature females. Each step in isolation was guided by bioassay. Isolation methods included extraction and solvent partitioning and separation methods included ultrafiltration and high-performance liquid chromatography. Uric acid was identified as the sperm-release pheromone that is discharged by the female with release of the eggs. The threshold concentration for sperm release by males was determined as 0.6 M.     

Kairomones for the egg parasiteTrichogramma evanescens Westwood

In observation-cage experiments some new contact kairomones for the egg parasiteTrichogramma evanescens Westwood are demonstrated.T. evanescens females search significantly longer on cabbage leaves treated with the wing scales of two hosts,Pieris brassicae L. andP. rapae L. Further, egg washes ofP. brassicae containing an oviposition deterrent pheromone for the butterflies, were found to have a contact-kairomonal effect on the parasite.T. evanescens females search significantly longer on cabbage leaves sprayed with a methanol or water wash ofP. brassicae eggs than on leaves treated with the solvent only.Hymenoptera: Trichogrammatidae.Lepidoptera: Pieridae.     

Squash leaf glandular trichome volatiles: Identification and influence on behavior of female pickleworm moth [Diaphania nitidalis (Stoll.)] (Lepidoptera: Pyralidae)

Fourteen volatile compounds occurring in leaf trichomes of yellow squash (Cucurbita pepo L. cv. Early Prolific Straightneck) were identified. These compounds accounted for 83.5% of the volatile matrix. Ubiquitous constituents of the epidermis (myristic, palmitic, and stearic acids,n-tricosane, andn-pentacosane) accounted for 73.7%; these compounds were not bioassayed. The volatileso-,m-, andp-xylene, toluene, 2-heptanone, (R)-(+)- and (S)-(–)-limonene, and germacrene D were tested for their influence on attraction and oviposition by the pickleworm moth (Diaphania nitidalis Stoll.). No single compound, except germacrene D, was attractive. (R)-(+)-Limonene and 2-heptanone were weakly repellent. Mixtures of the highly volatile fractions were as attractive as volatiles emanating from whole, intact leaves. Oviposition levels on treated artificial sites corresponded with levels of visitation. Oviposition was significantly stimulated by whole-leaf volatiles, and (S)-(–)-limonene caused a slight but significant reduction.Mention of a trade name or proprietary product does not constitute a warranty or guarantee by the U.S. Department of Agriculture, nor does it imply exclusion of other products that may also be suitable.     

4种杀螨剂对二斑叶螨抗性种群不同发育阶段的致毒作用研究

运用浸渍法和叶片残毒法测定了4种杀螨剂及其混剂对二斑叶螨抗性种群不同发育阶段的致毒作用。结果表明：阿维菌素对雌成螨的毒力最高，LC50为0．0864mg/L；其次为溴虫腈和阿维菌素＋哒螨灵（1：15），LC50分别为9．5377mg/L和1.4412mg/L。对卵的毒力溴虫腈最高，LC50为0.1223mg/L；其次为阿维菌素和阿维菌素＋哒螨灵（1：15），LC50分别为0.4425mg/L和0.6827mg/L。对二斑叶螨的室内控制效果依次为溴虫腈＞阿维菌素＋哒螨灵（1：15）＞哒螨灵＞阿维菌素＞哒螨灵＋甲氰菊酯（1：1）＞甲氰菊酯。     

蛋黄磷脂的提纯

利用蛋白质不溶或微溶于某些溶剂的特点,用混合溶剂萃取粗蛋黄磷脂制备精蛋黄磷脂的工艺,该工艺易于实现工业化生产,磷脂纯度可达98%以上。     

超高压改性对鸡蛋蛋白液起泡及物理性质的影响

采用超高压改性鸡蛋蛋白液,研究了压力、保压时间对蛋白液起泡性质和物理性质的影响结果表明,新鲜蛋白液在350MPa的静水压下处理15min后的起泡性质最好．此外,超高压改性还导致蛋白液的黏度和表面张力呈现升高后又急剧降低的趋势,并能够降低蛋白液的明度.     

Chemical mediation of egg capsule deposition by mud snails

Mud snails (Ilyanassa obsoleta = Nassarius obsoletus = Nassa obsoleta) deposit eggs in protective capsules on hard substrata in soft bottom environments. We studied sites of egg capsule deposition and snail movement responses to odors to determine if chemoreception plays a role in deposition site selection. From results of field surveys, laboratory experiments, and field experiments, we conclude that mud snails use chemoreception for capsule deposition. Attractive odors originate from mud snail and whelk egg capsules and from living bivalves. Evidence for attractive odors from conspecifics is equivocal. Capsules are deposited on living odor sources and nearby hard substrates. We hypothesize that deposition of capsules on living substrates increases the likelihood that embryos will survive by decreasing the chance of smothering of embryos by sediments.     

Drift and retention of pelagic spawning minnow eggs in a regulated river

Long‐distance drift of eggs and larvae has been identified as a possible cause of downstream displacement and poor recruitment of the endangered Rio Grande silvery minnow (Hybognathus amarus; silvery minnow). Seven experiments were conducted using artificial eggs to estimate silvery minnow egg drift and retention in the Albuquerque and Isleta reaches of the regulated Middle Rio Grande, New Mexico, USA over a range of flows during expected spawning times. Bead retention varied by reach, discharge, and shape of the hydrograph. Highest retention (6.9 and 9.7% per km in the Albuquerque and Isleta reaches, respectively) occurred on the ascending limb of a high flow in areas where there was substantial floodplain inundation. Retention was maximized at different flows in each reach (97 and 140 m³/s, respectively), possibly associated with reach‐specific floodplain inundation thresholds. Lowest retention in each reach (2.1 and 1.7%, respectively) occurred on the descending limb of low and high flows, respectively. Of the silvery minnow eggs produced in the combined Albuquerque and Isleta reaches in 2005, 8–14% are predicted to have been retained in the Albuquerque Reach (67 km) and 49–83% in the Isleta Reach (86 km) based on the distribution of adult fish and measured bead retention rates. Although silvery minnow propagules are capable of drifting long distances, our study suggests that considerable retention occurs in the Middle Rio Grande. Habitat restoration to increase channel habitat complexity, and flow management to promote floodplain inundation should help to retain a greater proportion of propagules in upstream reaches. Copyright © 2010 John Wiley & Sons, Ltd.