克氏原螯虾产业发展背景、现状与展望

综述了在我国克氏原螯虾的分布情况、资源的开发利用以及贸易状况。对2010年江苏南京等地发生的"龙虾门"事件进行了原因分析,指出我国克氏原螯虾产业化发展中存在的问题,提出了解决这些问题的对策,展望了克氏原螯虾产业发展的前景。

Establishment of BALB/c Mice Model for Food Allergy to Chinese Lobsters

[Objective] This study aimed to establish Balb/c mice model for food allergy caused by Chinese lobsters through using intraperitoneal injection for sensitization and explore methods for in vitro identification and evaluation of food allergy caused by Chinese lobsters. [Method] The 40 male Bal/c mice were divided into ovalbumin（OVA） positive control group, Coca＇s solution negative control group, blank control group and model group. Balb/c mice model was established by intraperitoneally injection of immunized Balb/c mice with OVA or Chinese lobster crude protein with aluminum hydroxide adjuvant. IgE and histamine levels in serum after the second challenge were determined by ELISA method, and the specific IgE antibody titer was determined by passive cutaneous anaphylaxis test（PCA）; additionally, spleen index and histological changes in the small intestine, as well as food allergy symptoms after challenge were also calculated or observed. [Results] After the last challenge, IgE content was（236.75 ±73.39） μg/L in the Chinese lobster crude protein group, revealing no difference with that in the OVA group, but significantly higher than that in either the Coca＇s solution group or the blank control group（P 0.01）;histamine content in serum in the Chinese lobster crude protein group was（406.55±232.79）, significantly higher than that in the blank control group（P0.01）. In the passive cutaneous anaphylaxis test, IgE antibody titer reached 1/16 after the last challenge in the Chinese lobster crude protein group. Spleen index in both Chinese lobster crude protein group and OVA group was significantly greater than that in either the Coca＇s solution group or the blank control group（P0.01）. What＇s more, infiltration of inflammatory cells like lymphocytes and eosnophils at the lamina propria of intestinal mucosa was also observed both Chinese lobster crude protein group and OVA group. [Conclusion] This study established Balb/c mice model for food allergy caused by Chinese lobsters; serum IgE and ELISA assay and specific IgE antibody titer in PCA test can be used for the in vitro identification and evaluation of food allergies caused by Chinese lobsters.

About the Conjecture of Felicitous Trees

A tree T is felicitous if there is a labelling l of its vertices with distinct integers from the set {0,1,2,…,｜E(T)｜}, so that the induced edge labelling l′ defined by l′(e)=l(u)+l(v) mod ｜E(T)｜ for each e=uv∈E(T), assigns each edge e a different label. In this paper, we constructively proved that more classes of trees are felicitous. In the end, we gave a conjecture that every lobster tree is felicitous.

Starvation on changes in growth and fatty acid composition of juvenile red swamp crawfish, Procambarus clarkii

The effect of starvation on physiological and biochemical indicators of body, muscle and hepatopancreas were investigated for juvenile red swamp crawfish （Procambarus clarkii）, and the results showed the effect was obvious. In a 70-day starvation experiment, mean body weight, exuvial rate, abdominal muscle ratio and hepatosomatic index decreased significantly. The percentage of protein, fat, ash and moisture were also significantly affected. The protein content decreased sharply at Day 30 onward and the percentage of fat decreased rapidly from Day 50 and on. The percentages of ash and moisture started to increase significantly at Day 40 and 30 respectively. After the starvation experiment, the hepatopancreatic total and neutral lipid content decreased slightly from 23.90% to 20.39% and 73.75% to 70.35%, while the hepatopancreatic polar lipid content increased from 23.81% to 27.32%. On the other hand, all the muscular total, neutral and polar lipid contents, and the muscular fatty acid compositions did not change significantly except for the hepatopancreatic fatty acid composition. The relative percentages of 14：0, 16：0, 16：1n-7 and 18：1n-9 were decreased by 55.17%, 11.11%, 8.5% and 6.70% from the initial values, and the relative percentages of 18：2n-6, 18：3n-3, 20：4n-6, 20：5n-3 and 22：6n-3 increased obviously from 5.2%, 3.9%,4, 2.4%, 10.6%, and 13.7% to 7.1%, 5.0%, 2.8%, 11.5%, and 14.4% respectively. Preference of utilization of fatty acids from hepatopancreas during starvation was as follows： 14：0〉16：0〉16：1n-7〉18：1n-9, and the conservation of highly unsaturated fatty acids was in the order of： 18：2n-6 〉18：3n-3〉20：4n-6〉20：5n-3〉22：6n-3.

Digestive enzyme activity and mRNA level of trypsin in embryonic redclaw crayfish, Cherax quadricarnatus

Abstract The digestive enzyme activity and mRNA level of trypsin during the embryonic development of Cherax quadricarinatus were analyzed using biochemical and Fluorogenic Quantitative PCR （FQ-PCR） methods. The results show that the activities of trypsin and chymotrypsin had two different change patterns. Trypsin specific activity increased rapidly in the early stages of development and still remained high in preparation for the hatch stage. However, chymotrypsin activity peaked in stage 4 of embryonic development and decreased significantly in the last stage. The mRNA level of trypsin was elevated in all stages and two peak values were observed in stages 2 and 5 respectively. The results indicate that trypsin is very important for the utilization of the yolk during embryonic development and for the assimilation of dietary protein for larvae. The gene of trypsin is probably regulated at transcriptional level. The mRNA levels of trypsin can reflect not only trypsin activity, but also the regulatory mechanism for expression of trypsin gene to a certain degree.

Characterization of Specific Spoilage Bacteria and Volatile Flavor Compounds of Flavored Crayfish

It is a common issue in the processing industry of crayfish that flavored crayfish stored at room temperature is perishable.In order to establish an effective putrid prediction mechanism,high-throughput sequencing and solid phase microextraction gas chromatography-mass spectrometry(SPME-GCMS)were used to analyse the microbial community structure and volatile flavor compounds of normal and putrid crayfish.The results showed that Aeromonas(57%),Macrococcus(7.7%),Vibrio sp.(6.6%),Acinetobacter(5%),Citrobacter(4.9%)and Enterobacter(1.49%)were the main bacterial genus in the refrigerated fresh crayfish(HNA).And Staphylococcus(17.04%),Aeromonas(4.46%),Xanthomonas(4.16%),Streptococcus(4.62%)and Enterococcus(2.77%)were the main bacterial genus in the marinated and refrigerated crayfish(HND).With the spoilage of samples(HNE and HNC),the diversity of bacteria decreased,and the specific spoilage bacteria grew rapidly,mainly Enterococcus,Bacillus,Lactobacillus,Leuconostoc,Weissella.Meanwhile,the volatile compounds in non-spoilage sample(HNA and HND)were mainly alkane compounds,aldehydes compound and esters compounds;and the volatile compounds in spoilage samples were mainly alcohols,acids,benzene compounds,terpenoids,N-containing compounds,S-containing compounds and ethers.This indicated that the contents and types of volatile compounds changed with the sample spoilage and deterioration.Correlation analysis results showed that Enterococcus,Lactobacillus and Bacillus were significantly positively correlated with alcohols,acids,benzene,terpenoids,N-containing compounds,S-containing compounds and ether compounds,while Aeromonas,Megasphaera,Acinetobacter,Citrobacter and Vibrio were significantly positively correlated with alkane compounds and esters compounds,and Leuconostoc were significantly positively correlated with alcohol compounds.These results can provide a theoretical guidance for the storage of cooked flavor crayfish at room temperature.

Crayfish Shell Waste as Safe Biosorbent for Removal of Cu^(2+)and Pb^(2+)from Synthetic Wastewater

Crayfish shell is an abundant natural waste and is also a potential biosorbent for pollutants,especially,heavy metals.In this study,the safety of the use of crayfish shell as a biosorbent was first assessed by release experiments involving primary heavy metal ions,such as Cu^(2+),Zn^(2+),and Cr^(3+),in aqueous solution under different environmental conditions.The release concentrations of heavy metals were dependent on pH,ionic strength,and humic acid;and the maximum release concentrations of heavy metals were still lower than the national standard.Specifically,Cu^(2+) and Pb^(2+) removal by crayfish shell in synthetic wastewater was investigated.The removal process involved biosorption,precipitation,and complexation,and the results indicate that crayfish shell is an excellent biosorbent for Cu^(2+) and Pb^(2+) removal.The precipitation step is particularly dependent on Ca species,pH,and temperature.The maximum removal capacities of Pb^(2+) and Cu^(2+) were 676.20 and 119.98 mg/g,respectively.The related precipitates and the generated complex products include Cu_(2)CO_(3)(OH)_(2),Ca_(2)CuO_(3),CuCO_(3),Pb_(2)CO_(3)(OH)_(2),CaPb_(3)O_(4),and PbCO_(3).

Preliminary Results of Crayfish Distribution and Diseases in Latvia

A lot of water reservoirs offer good natural conditions for crayfish breeding. Today there are four crayfish species present in Latvia--the European species noble crayfish （Astacus astacus）, narrow-clawed crayfish （Astacus leptodactylus）, the North American signal crayfish （Pacifastacus leniusculus） and spiny-cheek crayfish （Orconectes limosus）. In general, crayfish were found in 258 localities--lakes （175）, rivers and streams （66）, reservoirs, ponds and gravel-pits （17）. A. astacus in Latvia is the dominant crayfish species distributed in all regions. Narrow-clawed crayfish was registered since 1960s. North American signal crayfish was introduced due to its resistance to diseases, but spiny-cheek crayfish arrived from Lithuania waters spontaneously. The main threat for crayfish population is crayfish plague, initiated by mucus Aphanomyces astaci. Astacus astacus was more susceptible species in comparison with Pacifastacus leniusculus and Orconectes limosus. Though the North American signal crayfish and spiny-cheek crayfish were not only resistant, they were the carriers of this disease. The physical habitat alterations, pollution and overfishing are significant during the first year breeding period. Crayfish might serve as bacteria carriers and can cause substantial fish diseases （such as aeromonosis, flavobacteriosis）.

两个脚趾的“龙虾民族”

两个脚趾用得很出色 虽然曾经零星地听过一些关于津巴布韦两脚趾人的报道，但我第一次见到两脚趾人却不是在津巴布韦，而是在博茨瓦纳境内弗朗西斯敦市以北64公里的一个山谷中。这里距离津巴布韦和博茨瓦纳边境线仅2公里左右，遍地盖着非常原始的小泥屋，大约100个两脚趾人就平静地生活在这里。

“微”言“博”语来自博物微博的声音

@渐近人烟之野兽：造型太给力了。“猫总”这范儿，让我不禁想起施洋大律师、少剑波参谋长等等一系列老一代无产阶级革命家。

Structure and mechanical properties of pincers for freshwater lobster

The mineral phases and structure of pincer for the freshwater lobster were analyzed and observed by using X-ray diffraction and field-emission scanning electronic microscope with energy dispersive spectroscopy, and the mechanical properties of pincer were determined by using nano-indenter and micro-tribometer. The results showed that the pincers contained Ca, Mg, C, O, Na, etc. elements and there were many amorphous mineral phases in the lobster pincers. There were many concave hollows and convex domes with seta on the surface of pincer, and some spines were observed on the surface of seta, which exhibited non-smooth surface. The exoskeleton of pincer consisted of epicuticle, exocuticle and endocuticle, and the microstructure of exocuticle and endocuticle displayed the twisted plywood structure with chitin protein fibers. The mean hardness and elastic modulus on the surface of fresh pincers were 0.27 GPa and 5.28 GPa, respectively. With the increase in distance from the surface, the hardness and elastic modulus all decreased gradually. This indicated that the transition of hardness and elastic modulus occurred from exocuticle to endocuticle. When the heat treatment temperature was lower than 200°C, the values of hardness and elastic modulus fluctuated slightly, while they increased at the temperature beyond 200°C. As the pincers slid against Si3N4 balls in water and air, the friction coefficients in water were higher than those in air. The research could provide a bio-inspired basis for the structural design of composite materials and anti-friction surface.