Organic Carbon and Nitrogen Isoscapes of Reef Corals and Algal Symbionts: Relative Influences of Environmental Gradients and Heterotrophy.

The elemental (C/N) and stable isotopic (δ13C, δ15N) compositions and compound-specific δ15N values of amino acids (δ15NAA) were evaluated for coral holobionts as diagnostic tools to detect spatiotemporal environmental heterogeneity and its effects on coral health. Hermatypic coral samples of eight species were collected at 12 reef sites with differing levels of pollution stress. The C/N ratios, δ13C values, and δ15N values of coral tissues and endosymbiotic algae were determined for 193 coral holobionts, and the amino acid composition and δ15NAA values of selected samples were analyzed. δ15N values were influenced most by pollution stress, while C/N ratios and δ13C values depended most strongly on species. The results imply that δ13C and δ15N values are useful indicators for distinguishing the ecological niches of sympatric coral species based on microhabitat preference and resource selectivity. Using δ15NAA values, the trophic level (TL) of the examined coral samples was estimated to be 0.71 to 1.53, i.e., purely autotrophic to partially heterotrophic. Significant portions of the variation in bulk δ15N and δ13C values could be explained by the influence of heterotrophy. The TL of symbionts covaried with that of their hosts, implying that amino acids acquired through host heterotrophy are translocated to symbionts. Dependence on heterotrophy was stronger at polluted sites, indicating that the ecological role of corals changes in response to eutrophication.

Assessment of coastal turbidity improvement potential by terrigenous sediment load reduction and its implications on seagrass inhabitable area in Banate Bay, central Philippines.

This paper demonstrates the effects of terrigenous sediment load reduction by watershed managements on coastal turbidity in Banate Bay, Iloilo located in central Philippines, using field observations and numerical simulations. Measurements of the total suspended solid and particulate organic carbon indicated that the bulk component of the coastal turbidity comprised terrigenous mineral particles rather than phytoplankton at the rise of the river after heavy rain. The suspended sediment concentration and underwater light intensity were simulated by an atmosphere-watershed-coastal ocean model to investigate the contribution of the terrigenous sediment load to the coastal turbidity in rainy season. The coastal sediment simulation indicated that the turbidity in Banate Bay is highly impacted by terrigenous sediment inputs from distant watersheds, which are transported to the bay by coastal currents. In contrast, the contributions of sediment loads from the adjacent watersheds to the bay turbidity were limited. The simulation also indicated that the majority of the bay is not inhabitable for seagrasses due to limited light availability caused by the high turbidity. Scenario analysis of the sediment load reduction demonstrated that significant reduction of turbidity and improvement of light penetration are conditionally expected only when the remediation is implemented with cooperative management of a series of neighboring watersheds because of the significant contributions of sediment loads from multiple basins.

Familial acanthosis nigricans with the FGFR3 mutation: Differences of pigmentation between male and female patients.

Familial acanthosis nigricans caused by the mutation of the fibroblast growth factor receptor 3 (FGFR3) gene is characterized by short stature, hypochondroplasia and acanthosis nigricans. We herein report a Japanese family that showed a missense mutation of c.1948A>C (p.K650Q) in FGFR3. The pigmentation of acanthosis nigricans was more prominent in male patients than in female patients in this family. We immunohistochemically analyzed the distribution of melanocytes. Although pigmentation in the basal layer was denser in the proband, there was no difference in the distribution and number of melanocytes.

Phosphorus as a driver of nitrogen limitation and sustained eutrophic conditions in Bolinao and Anda, Philippines, a mariculture-impacted tropical coastal area.

The dynamics of nitrogen (N) and phosphorus (P) was studied in mariculture areas around Bolinao and Anda, Philippines to examine its possible link to recurring algal blooms, hypoxia and fish kills. They occur despite regulation on number of fish farm structures in Bolinao to improve water quality after 2002, following a massive fish kill in the area. Based on spatiotemporal surveys, coastal waters remained eutrophic a decade after imposing regulation, primarily due to decomposition of uneaten and undigested feeds, and fish excretions. Relative to Redfield ratio (16), these materials are enriched in P, resulting in low N/P ratios (~6.6) of regenerated nutrients. Dissolved inorganic P (DIP) in the water reached 4µM during the dry season, likely exacerbated by increase in fish farm structures in Anda. DIP enrichment created an N-limited condition that is highly susceptible to sporadic algal blooms whenever N is supplied from freshwater during the wet season.

Requirement of SIRPα for protective immunity against Leishmania major.

Signal regulatory protein α (SIRPα) is a transmembrane protein that binds the protein tyrosine phosphatases SHP-1 and SHP-2 through its cytoplasmic region and is abundantly expressed on dendritic cells and macrophages. Wild-type (WT) C57BL/6 mice are known to be resistant to Leishmania major infection. We here found that C57BL/6 mice that express a mutant version of SIRPα lacking most of the cytoplasmic region manifested increased susceptibility to L. major infection, characterized by the marked infiltration of inflammatory cells in the infected lesions. The numbers of the parasites in footpads, draining lymph nodes and spleens were also markedly increased in the infected SIRPα mutant mice, compared with those for the infected WT mice. In addition, soluble leishmanial antigen-induced production of IFN-γ by splenocytes of the infected SIRPα mutant mice was markedly reduced. By contrast, the ability of macrophages of SIRPα mutant mice to produce nitric oxide in response to IFN-γ was almost equivalent to that of macrophages from WT mice. These results suggest that SIRPα is indispensable for protective immunity against L. major by the induction of Th1 response.

Phenotypic plasticity and sexual dimorphism in size at post-juvenile metamorphosis: common-garden rearing of an intertidal gastropod with determinate growth.

Proximate factors of the intraspecific variation in molluscan shell morphology have long received attention in biology. The intertidal gastropod Monetaria annulus (Mollusca; Gastropoda; Cypraeidae) is particularly suitable for the study of variation in body size, because this species is a determinate grower in the sense that soft-body size shows no further increase after the juvenile stage. Cross-sectional field surveys on post-juvenile individuals have indicated that the mean body size varies widely among populations and is larger in females than in males within populations. To examine whether these patterns are due to genetic differences, we conducted a common-garden rearing experiment with juvenile individuals collected from two populations on Okinawa Island. After adjusting for among-individual differences in initial degree of development, statistical analyses revealed that this species exhibits female-biased sexual size dimorphism mediated by a longer development time rather than by faster growth rates in females. Although wild individuals show a remarkable size difference between populations, no size difference was found between the populations in the individuals reared in a common-garden condition. This result suggests that the among-population size difference does not have a genetic basis and is caused by phenotypic plasticity based on environmental heterogeneity among habitats.