Reduction in Activity/Gene Expression of Anthocyanin Degradation Enzymes in Lychee Pericarp is Responsible for the Color Protection of the Fruit by Heat and Acid Treatment

Heat and acid treatments were reported to be a promising substitute for SO2 fumigation in color protection of postharvest lychee （Litchi chinensis） fruits, but the mechanism was not clear. In the present study, hot water （70℃） dipping followed by immersion in 2% HC1 （heat-acid） substantially protected the red color of the fruit during storage at 25℃ and inhibited anthocyanin degradation while hot water dipping alone （heat） led to rapidly browning and about 90% loss in anthocyanin content. The pH values in the pericarp of the heat-acid treated fruit dropped to 3.2, while the values maintained around 5.0 in the heat-treated and control fruit. No significantly different pH values were detected among the arils of heat-acid, heat treated and control fruit. Heat-acid treatment dramatically reduced the activities of anthocyanin degradation enzyme （ADE）, peroxidase （POD） and polyphenol oxidase in the pericarp. A marked reduction in LcPOD gene expression was also detected in heat-acid treated fruit, in contrast, induction was found in heat treated fruit. The pericarp of heat-acid treated fruit exhibited significantly lower respiration rate but faster water loss than that of the untreated or heat treated fruit. Taken together, heat treatment triggered quick browning and anthocyanin loss in lychee fruit, while heat-acid treatment protected the fruit color by a great reduction in the activities/gene expression of anthocyanin degradation enzymes and acidification of lychee pericarp.

Progress in Research on Insect Olfactory Perception of Habitat Odor Molecules

A highly sensitive olfactory system allows insects to precisely identify and position volatile compounds from different sources in their habitats,and plays a crucial role in their foraging,mating,and oviposition activities.During evolution,insects have successfully developed a large and complex olfactory system to adapt to heterogeneous environments,enabling the maintenance of inset population.A comprehensive examination of the olfactory system of insects may therefore yield novel insights into the development of innovative pest control and prevention strategies,as well as the study of olfactory mechanisms in vertebrates and even humans.This paper outlines the current state of research into the signal transduction mechanism by which insects perceive the olfactory molecules of their habitats.The aim of this review is to provide a reference point for future studies into the olfactory perception mechanism and its potential applications in pest management.

Insights into seasonal variation of litter decomposition and related soil degradative enzyme activities in subtropical forest in China

We used a litterbag method to investigate litter decomposition and related soil degradative enzyme activities across four seasons in a broad-leaved forest and a coniferous forest on Zijin Mountain in sub-tropical China. Across four seasons, we quantified litter mass losses, soil pH values, and related soil degradative enzyme activities. Litter decomposition rates differed significantly by season. Litter decomposi- tion rates of broadleaf forest leaves were higher than for coniferous for- ests needles across four seasons, and maximal differences in litter de- composition rates between the two litter types were found in spring.

Analysis of Calcium Content, Hormones, and Degrading Enzymes in Tomato Pedicel Explants During Calcium-Inhibited Abscission

This study was designed to analyze the changes of phytohormone concentrations, calcium fraction, and the activities of degrading enzymes during calcium-inhibited and ethyleneglycol-bis-（β-aminoethyl ether）N, N＇-tetraacetic acid （EGTA）-induced abscission of tomato pedicel explants. Added calcium caused an increase in the total calcium content within the abscission zone and produced a corresponding reduction （20%） in pedicel explant abscission. As expected, EGTA treatment produced the opposite effect and resulted in a decrease in the total calcium content, while accelerating abscission of pedicel explants. Hormone analysis revealed that indole-3-acetic acid （IAA） concentrations in the abscission zone first decreased and then increased before the occurrence of abscission in all treatments, with the greatest effect produced by addition of EGTA. Similarly, abscisic acid （ABA）, and gibberellin （GA1＋3） concentrations, and ethylene production were elevated in the abscission zone during the first 16 h before abscission when explants imbibed EGTA. With calcium treatment, the concentrations of ABA, ethylene, and GA1＋3 also increased in pedicels throughout the first 16 h following exposure, but the increase was slower and less dramatic than with EGTA. Both cellulase and polygalacturonase were induced in the explants during abscission and the activities were also strengthened by treatment with EGTA. Calciumtreated explants produced lower hydrolysing enzyme activities than controls throughout abscission. Calcium played a role of mediating hormone balance and degrading enzymes activities and affected on abscission.

Pathogenicity of Cell Wall Degrading Enzymes Produced by Botryodiplodia theobromae Pat. against Mangoes

[ Objective ] This study aimed to confirm the roles of cell wall degrading enzymes （CWDEs） produced by Botryodiplodia theobromae Pat. in the infec- tion of mango fruits. [ Method] Change of activities of five types of CWDEs produced by B. theobromae Pat. were studied under both in vitro culture and inocula- tion conditions, along with the pathogenicity and the ability of producing CWDEs of four post-harvest fangal pathogens（B, theobromae Pat. , Colletotrichum gloeos- porioides Penz. , Phomopsis mangiferae Ahmad and Dothiorella dominicana Pet. et Cif. ） which cause stem-end rot of mangoes. [ Result] B. theobromae Pat. was a- ble to produce polygalacturonase（PG）, pectinmethylgalacturonase（PMG）, polygalacturonic acid trans-eliminase （PGTE）, pectin methyltrans-eliminase （PMTE） and cellulase （ Cx. ） under both in vitro culture and inoculation conditions, of which activities of PG, Cx and PMG were significantly higher in than that in either PGTE or PMTE. Among three primary CWDEs, the peak of activities of PG and Cx appeared earlier and that of PMG occured later. The pathogenicity of B. theo- bromae Pat. was significantly higher than that of any other three pathogens; it is the same with the abilities of producing pectinase. [ Conclusion] This paper pro- vides theoretical bases for further exploring the mechanism of host-pathogen interaction and decreasing the post-harvest loss of mango fruits.

The quantity of OA and activity of cellulase and polygalacturonase are involved in variation of virulence in Sclerotium rolfsii

In order to understand the pathogenic mechanisms of Sclerotium rolfsii on peanut and to analyze the variation of virulence in S.rolfsii strains,the highly virulent strain(ZY2)and weakly virulent strain(GP3-1)were investigated under both in vivo and in vitro conditions.The results indicated that S.rolfsii directly infected peanut by producing infection cushions.ZY2 formed infection cushions earlier than GP3-1,and ZY2 produced a greater number of infection cushions compare to GP3-1.Both strains could utilize cellulose,xylose,or polygalacturonic acid in the Czapek medium.The activities of cellulase(CL)and polygalacturonase(PG)in the inoculated peanut stems increased significantly at 9 h after inoculation.The activities of CL and PG produced by ZY2 in the inoculated stems were significantly higher than that produced by GP3-1.Both strains could produce oxalic acid(OA),and the content of OA produced by ZY2 in the inoculated stems was higher than that produced by GP3-1.In summary,it suggested that S.rolfsii destroyed peanut cells through physical and biochemical factors by secreting a large amount of OA,CL and PG during the formation of infection cushions.The difference in OA content,activity of CL and PG produced by highly and weakly virulent strains played important roles in variation of virulence.

糖胺聚糖降解菌株的筛选及鉴定

以土壤为材料,用透明质酸和硫酸软骨素为唯一碳源富集分离菌株,通过BSA-乙酸平板显色法及比色定糖法进行筛选。从80份土壤中筛选出13株糖胺聚糖降解活性的菌株并对其进行了16S rDNA测序鉴定。结果表明,筛选到13株糖胺聚糖降解菌株均具有透明质酸酶和硫酸软骨素酶活性;获得8株尚未报导过的产糖胺聚糖降解酶活性菌株。本研究为开发新型的糖胺聚糖降解酶提供参考。

Mycoparasitism of Nematode-Trapping Fungus Monacrosporium ellipsosporumand Its Biochemical Basis

Monacrosporium ellipsosporum, a nematode-trapping fungus, was isolated by baiting with sclerotiaof Sclerotinia sclerotiorum in soil from a tobacco field in Yuxi, Yunnan Province. Colonizationfrequency of the sclerotia by the fungus was 18% in natural soil. Reinoculation tests byplacing surface-sterilized sclerotia on fungal cultures for two weeks and then surface-sterilized again led to 32% sclerotia be infected. Dual culture tests in PDA plates did notgive rise to a suppression zone between the colonies of M. ellipsosporum and its counterpartfungi S. sclerotiorum and Rhizoctonia solani, suggesting there was little or no nutritionalcompetition and absent of antifungal compounds. However, M. ellipsosporum could grow overabsent of S. sclerotiorum and R. solani, and significantly inhibited their growth on agarplates. Scanning electron and light microscopic observations showed that hyphae of M. ellipsosporumgrew along and appressed on hypha of S. sclerotiorum and coiled around hyphae of R. solani.Assays of cell wall-degrading enzymes showed that M. ellipsosporum grew well in chitin agarmedia, with clear transparent hydrolysis zones. Activities of total chitinase, exo-chitinase,β-1, 3-glucanase and protease were 140.2±11.9, 82.9±4.1, 111.2±7.6 and 76.1±4.3 U respect-ively, after incubation for 4 days at 30 ℃ in liquid media containing ground sclerotia of S.sclerotiorum as sole nutrient source. These enzymes might be important in the mycoparasiticactivity of M. ellipsosporum.

Intranasal neprilysin rapidly eliminates amyloid-beta plaques, but causes plaque compensations: the explanation why the amyloid-beta cascade may fail?

Neurodegenerative brain disorders are a major burden in our society,such as Alzheimer´s disease.In order to repair or prevent such diseases,drugs are designed which enter the brain,but the blood-brain barrier limits their entry and the search for alternative pathways is important.Recently,we reported that intranasal delivery of the amyloid-beta degrading enzyme neprilysin eliminated amyloid-beta plaques in transgenic Alzheimer´s disease mice.This review describes the anatomical structure of the intranasal pathway,explains the intranasal delivery of pure neprilysin,cell-loaded neprilysin(platelets)and collagen-embedded neprilysin to destruct amyloid-beta plaques in Alzheimer´s disease in transgenic APP_SweDI mice and hypothesizes why this may cause compensation and why the amyloid-beta cascade hypothesis may fail.

The cause of germination increases the phenolic compound contents of Tartary buckwheat(Fagopyrum tataricum)

In order to study the changes and mechanism of phenolic compounds during Tartary buckwheat germination,the dynamic changes of phenolic compounds were analyzed,and the activities of enzymes that regulate phenolic compound biosynthesis and degradation were monitored.Total phenolics and total flavonoids presented an interesting dynamic trend with the extension of the germination time,and rutin,gallic acid,chlorogenic acid as well as 2,3,4-trihydroxybenzoic acid contents showed an increasing trend during germination period,the contents were up to(2663.4±61.1),(449.12±5.26),(99.953±7.800)and(50.442±1.477)mg/100 g DW,respectively.Phenylalanine ammonia lyase(PAL)and chalcone isomerase(CHI)are dominant enzymes in regulating phenolic compound biosynthesis,which showed an increasing trend.Rutin degrading enzyme(RDEs)is the key enzyme in regulating phenolic compound degradation,which showed a decreasing trend.These results suggested that germination processing increases the phenolic compound contents of Tartary buckwheat,which may be regulated by the activation of PAL,CHI and the inhibition of RDEs.