Geographical range size and host specificity in ectoparasites: a case study with Amphipsylla fleas and rodent hosts

Aim  To identify the factors that determine the geographical range sizes of ectoparasites with different degrees of host specificity.
Location  The study used data on the distributions of fleas of the genus Amphipsylla and their rodent hosts across the Holarctic.
Methods  All known points of occurrence of 32 flea species and 51 species of their rodent hosts were mapped. The shape and size of the geographical range of each species were estimated using a combination of the minimal convex polygon technique and modelling with the garp algorithm. Factors determining the geographical range sizes of the fleas were identified using stepwise multiple regression analysis.
Results  The geographical range size of fleas that are strongly host-specific across their entire ranges correlated positively with the geographical range size of the fleas' principal hosts, and negatively with the geographical range size of the fleas' potential competitors. The geographical range sizes of both (1) fleas that are locally host-specific but that shift their host preferences geographically, and (2) host-opportunistic fleas were positively correlated only with the area of the geographical ranges of their principal hosts. Strongly host-specific fleas occupied 0.2–80.0% of the geographical range of their principal hosts, whereas this figure was 0.9–83.7% in locally host-specific fleas and 16.6–63.7% in host-opportunistic fleas.
Main conclusions  The main determinant of the geographical range size of a flea species is the size of the geographical range of its hosts. The role of potential competitors in determining the geographical range size is stronger in host-specific than in host-opportunistic fleas. Cases in which the geographical range of a parasite is smaller than the geographical range(s) of its host(s) owing to narrower parasite environmental tolerances are much more frequent in host-opportunistic than in host-specific fleas.     

Bioactive compounds from Rumex plants

Two new naphthalene acylglucosides, rumexneposides A (1) and B (2), together with 12 known compounds (3-14), were isolated from the roots of Rumex nepalensis. Their structures were established by chemical and spectroscopic methods. The biological activities of compounds 1-14 as well as an additional 11 compounds previously isolated from R. nepalensis and Rumex hastatus (15–25) were evaluated against Mycobacterium tuberculosis, para-aminobenzoic acid (pAba) pathway, and a panel of human cancer cell lines. The results showed that compound 15 was the most active against M. tuberculosis with an MIC value of 2.85 μM similar to that of isoniazid. Compound 5 could inhibit pAba synthetic pathway with an MIC value of 12.6 μM, comparable to that of positive control abyssomicin C, representing a new example of the rare pAba pathway inhibitors.     

Marine fouling on floating installations west of Dongsha Islands,the northern South China Sea

Marine fouling on floating installations west of Dongsha Islands, the northern South China Sea, was investigated from August 1987 to October 1990. Two buoy stations were deployed at approximately 110 km and 115 km west of Dongshadao, Dongsha Islands, anchored in water at 325 and 345 m depths, and exposed for 8 and 12 months. The experimental panels were fixed on iron structure frames which were connected to the buoy and its mooring system immersed in water at different depths, and retrieved after 4, 8 and 12 months of exposure. Fouling organisms colonizing the buoys and their mooring systems were sampled after 8 and 12 months of deployment. A total of 86 species was collected and identified at these two stations and the fouling community showed a typical oceanic characteristics. Most of the species were mainly found in the top 50 m depth and a striking vertical zonation of species was also observed with depth. The distance from offshore is a major factor in determining the fouling community composition. In terms of biomass, the fouling community was dominated by pedunculate barnacles, hydroids, and algae, followed by common oysters, pearl oysters and acorn barnacles. Biomass of hard fouling organisms increased over time. Under the influence of hydrological currents propagules of communities around the Dongsha Islands may also affect the development of the fouling communities in the offshore waters.     

Early B-cell factors involve in the tumorigenesis and predict the overall survival of gastric cancer

Gastric cancer (GC) is a heavy health burden around the world, which is the fifth most frequent tumor and leads to the third most common cancer-related deaths. It is urgent to identify prognostic markers as the guideline for personalized treatment and follow-up. We accessed the prognostic value of Early B-cell factors (EBFs) in GC. A total of 415 GC tissues and 34 normal tissues from The Cancer Genome Atlas Stomach Adenocarcinoma (TCGA-STAD) cohort, 616 external patients from {"type":"entrez-geo","attrs":{"text":"GSE15459","term_id":"15459"}}GSE15459, {"type":"entrez-geo","attrs":{"text":"GSE22377","term_id":"22377"}}GSE22377, {"type":"entrez-geo","attrs":{"text":"GSE51105","term_id":"51105"}}GSE51105, {"type":"entrez-geo","attrs":{"text":"GSE62245","term_id":"62245"}}GSE62245 were enrolled for analysis. Univariate and multivariate Cox regression analyses were employed to evaluate the sole and integrative prognostic value of EBFs, respectively. Genetic alterations, DNA methylation of EBFs were also evaluated, as well as the involved signaling pathways. We revealed that increased EBFs associated with the poor prognosis of GC patients, the prognostic model was established in TCGA-STAD cohort, and validated in Gene Expression Omnibus (GEO) cohorts, with effectiveness in both HER2 positive and negative patients. DNA methylation was involved in the impact on prognosis. Cell cycle, immune-associated, and MAPK pathways were influenced by EBFs. Anti-CTLA4 immunotherapy is more suitable for EBFs determining high-risk groups, but not anti-PD-1/PD-L1 therapy. 5-Fluorouracil, methotrexate, vorinostat are suitable to inhibit the function of EBFs. Our new findings provide novel insight into the prediction of prognosis and clinical treatment of GC patients based on EBFs.