Nitrogenous Sesquiterpenoids from the South China Sea Nudibranch Hexabranchus sanguineus and Its Possible Sponge-Prey Acanthella cavernosa: Chiral Separation, Stereochemistry and Chemical Ecology

A detailed chemical investigation of the South China Sea nudibranch Hexabranchus sanguineus,as well as its possible sponge-prey Acanthella cavernosa,led to the isolation of fifteen new nitrogenous sesquiterpenoids,namely ximaocavernosins A-0,including seven cadinanes(1-7),seven spiroaxanes(12-18)and one aromadendrane(19),together with thirteen known related compounds(8-11 and 20-28).

An Explorer of Chemical Biology of Plant Natural Products in Southwest China,Xiaojiang Hao

Xiaojiang Hao,who obtained Master Degree from Kunming Institute of Botany(KIB),Chinese Academy of Sciences(CAS)in 1985,and Doctor in Pharmacy degree in Pharmacy from Institute for Chemical Research,Kyoto University,in 1990,was born in Chongqing in July,1951.In 1991,he returned to KIB,CAS,as an Associate professor and served as the chair of the Department of Phytochemistry.In 1994,he was promoted to a full professor at the current institute.He served as the Deputy Director of KIB and the Director of Open Laboratory of Phytochemistry from 1995 to 1997,and the Director of KIB from 1997 to 2005.Professor Hao has published more than 450 peer-reviewed SCI papers,which have been cited over 6000 times.He has obtained one PCT patent and 23 patents in China.Due to his tremendous efforts,one candidate drug,phenchlobenpyrrone,has entered the Phase II clinical trail for the treatment of Alzheimer’s disease.Moreover,he won the First Prize of Natural Sciences in Yunnan Province for three times,and Ho Leung Ho Lee Fund Science and Technology Innovation Award in 2017.

A study on the interactions among several plant secondary compounds and aphids

The research, focused on the specific interactions among seven plant secondary compounds and aphids, was carried out and the preliminary results showed: (1) 'T-typed tube method' was regarded as the best method compared with others designed to observe the interactions. (2) Cabbage aphid was able to be attracted by laurolene while it was not susceptible to α-pinene, β-pinene and diamylene. (3) Gossypol, a major secondary substance in cotton, was able to be implicated as feeding attractant to cotton aphid. (4) Rutin might be implicated repellent to cotton aphid.

Characterization of sugar diversity in floral and extra-floral nectar from the Coastal Coral Tree(Erythrina caffra Thunb.)in Southern California

The Coastal Coral Tree (Erythrina caffra Thunb.) produces floral nectar (FN) that serves to attract pollinating insects, but also secretes nectar from extra-floral (EFN) glands that serves to attract predatory insects, such as ants. While studies on myrmecophytes (i.e. specialized plants that attract and interact with ants) have primarily focused on interspecific evaluations of EFN chemistry, the Coastal Coral tree offers an opportunity to contrast intraspecific nectar chemistry with differing evolutionary and ecological functions. We hypothesized that the richness of (molecular) sugar species, relative concentrations, and diversity of sugars in FN and foliar EFN would diverge due to differences in the ecological role of the two types of nectar. High performance liquid chromatography with refractive index detection was used to identify the richness of sugar species (based on retention time), measure the relative concentrations, and evaluate the diversity of sugars in FN and foliar EFN secretions. We detected sugar species unique to each gland type and reported significant differences in the relative concentration of one sugar species common to both gland types. While the mean diversity index of sugars was similar for both gland types, the diversity of foliar EFN sugars was significantly more variable than that of FN sugars. The composition of FN showed little variation, and was reflective of its fundamental role in plant reproduction. Foliar EFN, however, demonstrated the variability expected of a context-dependent myrmecophyte that interacts with a facultative ant species assemblage across a mosaic of abiotic and biotic conditions.

Plant Terpenoids： Biosynthesis and Ecological Functions

Among plant secondary metabolites terpenolds are a structurally most diverse group; they function as phytoalexins In plant direct defense, or as signals In Indirect defense responses which involves herbivores and their natural enemies. In recent years, more and more attention has been paid to the Investigation of the ecological role of plant terpenolds. The biosynthesis pathways of monoterpenes, sesquiterpenes, and diterpenes Include the synthesis of C5 precursor isopentenyl diphosphate （IPP） and Its allylic isomer dlmethylallyl dlphosphate （DMAPP）, the synthesis of the immediate diphosphate precursors, and the formation of the diverse terpenoids. Terpene synthases （TPSs） play a key role In volatile terpene synthesis. By expression of the TPS genes, significant achievements have been made on metabolic engineering to Increase terpenoid production. This review mainly summarizes the recent research progress In elucidating the ecological role of terpenoids and characterization of the enzymes Involved in the terpenold biosynthesis. Spatial and temporal regulations of terpenoids metabolism are also discussed.

Behavioral evidence for contextual olfactory-mediated avoidance of the ubiquitous phytopathogen Botrytis cinerea by Drosophila suzukii

Herbivorous insects may benefit from avoiding the smell produced by phytopathogens infecting plant host tissue if the infected tissue reduces insect fitness.However,in many cases the same species of phytopathogen can also infect host plant tissues that do not directly affect herbivore fitness.Thus,insects may benefit from differentiating between pathogen odors emanating from food and nonfood tissues.This is based on the hypothesis that unecessarily staying attentive to pathogen odor from nonfood tissue may incur opportunity costs associated with not responding to other important survival functions.In this study adults of Drosophila suzukii Matsumura,an invasive larval frugivore,showed reduced attraction to the odor of raspberry fruit,a food tissue,when infected with Botrytis cinerea Pers.,a ubiquitous phytopathogen,in favor of odors of uninfected raspberry fruit.Moreover,D.suzukii oviposited fewer eggs on infected raspberry fruit relative to uninfected raspberry fruit.Larval survival and adult size after eclosion were significantly reduced when reared on B.cinerea-infected raspberry relative to uninfected fruit.Interestingly,when the behavioral choice experiment was repeated using Botrytis-infected vsuninfected strawberry leaves,a nonfood tissue,in combination with fresh raspberry fruit,odor from B.cinerea-infected leaves did not reduce D.suzukii attraction to raspberries rel-ative to raspberries with uninfected leaves.These behavioral results illustrate the important role context can play in odor-mediated interactions between insects,plants and microbes.We discuss implications of our findings for developing a repellent that can be useful for the management of D.suzukii.

Male Burmese pythons follow female scent trails and show sex-specific behaviors

Animals communicate with potential mates using species-specific signals,and pheromones are powerful sexu­al signals that modify conspecific behavior to facilitate mate location.Among the vertebrates,snakes are espe­cially adept in mate searching via chemical trailing,which is particularly relevant given that many snake spe­cies are invasive outside their native ranges.Chemical signals used in mate choice are,thus,potentially valuable tools for management of invasive snake species.The Burmese python(Python bivittatus)is an invasive snake in the Florida Everglades where it is negatively impacting native fauna.In this study,we sought to:(i)deter­mine if males can follow conspecific chemical trails in a Y-maze;and(ii)describe the mate searching behav­iors exhibited by males while trailing.All males consistently followed a single female scent trail in the maze,but when only a male scent trail was present they did not discriminate between the male and blank arms.Rate of tongue-flicking,a proxy for chemosensory sampling,was also marginally higher when males were following female versus male scent trails.However,when both female and male scent trails were simultaneously present in the Y-maze,males did not show a preference for the female arm,although the tongue-flick rate was higher in the female-only trial compared to female versus male.Analyses of multiple male behaviors individually and us­ing an ethogram revealed that behaviors were more frequent and complex in the female-only trials compared to male-only trials.Additional behavioral trials are needed to determine if an effective pheromonal approach to Burmese python management is possible.

Antibacterial and bioiflm inhibitory activities of bacteria associated with polychaetes

Objective:To study the antibacterial and antibiofilm activities expressed by epibiotic bacteria associated with the polychaetes Platynereis dumerilii and Syllis sp.Methods:A total of 32 cultivable bacterial strains were isolated from the two polychaete species.The crude extracts were tested for antibacterial activity and biofilm inhibitory activity against pathogenic and biofilm-forming bacterial strains.Extracts of the strains which showed strong activity were analyzed by thin-layer chromatography(TLC)and the bacterial strains were identified based on 16S rRNA gene sequencing.Results:Extracts of 13 bacterial strains showed inhibitory activity against pathogenic and biofilm-forming bacteria.The crude extracts also affected the synthesis of extracellular polymeric substances and cell surface hydrophobicity of the Alteromonas sp.isolated from marine biofilm.The adhesion of Alteromonas sp.on glass surface showed significant variation between surface-associated bacterial crude extract treatment and control groups.Among the 13 bacteria,two strains PA8 and PA19 were further analyzed for bioactive fractions.Thinlayer chromatography indicated the presence of a single active fraction in the crude extract of both the bacterial strains.The epibiotic bacterial strains P8 and P19 were identified as Exiguobacterium sp.and Actinobacterium sp.respectively based on 16S rRNA gene sequencing.Conclusions:The present study indicates that bacteria associated with marine invertebrates inhabiting the coastal waters could be used as a potential source for the isolation of bioactive metabolites.