Pigmented Nanoflagellates Grazing on <Emphasis Type="Italic">Synechococcus</Emphasis>: Seasonal Variations and Effect of Flagellate Size in the Coastal Ecosystem of Subtropical Western Pacific

We investigated seasonal variation of grazing impact of the pigmented nanoflagellates (PNF) with different sizes upon Synechococcus in the subtropical western Pacific coastal waters using grazing experiments with fluorescently labeled Synechococcus (FLS). For total PNF, conspicuous seasonal variations of ingestion rates on Synechococcus were found, and a functional response was observed. To further investigate the impact of different size groups, we separated the PNF into four categories (<3, 3–5, 5–10, and >10 μm). Our results indicated that the smallest PNF (<3 μm PNF) did not ingest FLS and was considered autotrophic. PNF of 3–5 μm in size made up most of the PNF community; however, their ingestion on Synechococcus was too low (0.1–1.9 Syn PNF⁻¹ h⁻¹) to support their growth, and they had to depend on other prey or photosynthesis to survive. The ingestion rate of the 3–5 μm group exhibited no significant seasonal variation; by contrast, the ingestion rates of 5–10 and >10 μm PNFs showed significant seasonal variation. During the warm season, 3–5 μm PNF were responsible for the grazing of 12% of Synechococcus production, 5–10 μm PNF for 48%, and >10 μm PNF for 2%. Taken together, our results demonstrate that the PNF of 3–10 μm consumed most Synechococcus during the warm season and exhibited a significant functional response to the increase in prey concentration.     

Dibenzocyclooctadiene lignans from Kadsura philippinensis

Lignans with the dibenzocyclooctadiene skeleton, kadsuphilols I-L, and one C₁₉-homolignan, kadsuphilol M, were isolated by chromatographic fractionation of an ethyl acetate extract of the aerial parts of Kadsura philippinensis. Their structures were elucidated through extensive spectroscopic methods, including HRESIMS and 2D NMR experiments (HMQC, COSY and HMBC). The stereochemistry at the chiral centers and the biphenyl moist, were determined using NOESY, as well as analysis of CD spectra, respectively. The relative configuration of heteroclitin J was confirmed by single crystal X-ray crystallographic analysis. The in vitro radical-scavenging activities of these compounds by using DPPH were evaluated.     

Enhanced levan production using chitin-binding domain fused levansucrase immobilized on chitin beads

Levan is a homopolymer of fructose which can be produced by the transfructosylation reaction of levansucrase (EC 2.4.1.10) from sucrose. In particular, levan synthesized by Zymomonas mobilis has found a wide and potential application in the food and pharmaceutical industry. In this study, the immobilization of Z. mobilis levansucrae (encoded by levU) was attempted for repeated production of levan. By fusion levU with the chitin-binding domain (ChBD), the hybrid protein was overproduced in a soluble form in Escherichia coli. After direct absorption of the protein mixture from E. coli onto chitin beads, levansucrase tagged with ChBD was found to specifically attach to the affinity matrix. Subsequent analysis indicated that the linkage between the enzyme and chitin beads was substantially stable. Furthermore, with 20% sucrose, the production of levan was enhanced by 60% to reach 83 g/l using the immobilized levansucrase as compared to that by the free counterpart. This production yield accounts for 41.5% conversion yield (g/g) on the basis of sucrose. After all, a total production of levan with 480 g/l was obtained by recycling of the immobilized enzyme for seven times. It is apparent that this approach offers a promising way for levan production by Z. mobilis levansucrase immobilized on chitin beads.     

Rethinking ‘style’ for historians and philosophers of science: converging lessons from sexuality, translation, and East Asian studies

Historians and philosophers of science have furnished a wide array of theoretical-historiographical terms to emphasize the discontinuities among different systems of knowledge. Some of the most famous include Thomas Kuhn’s “paradigm”, Michel Foucault’s “episteme”, and the notion of “styles of reasoning” more recently developed by Ian Hacking and Arnold Davidson. This paper takes up this theoretical-historiographical thread by assessing the values and limitations of the notion of “style” for the historical and philosophical study of science. Specifically, reflecting on various methodological and theoretical concerns prompted by sexuality, translation, and East Asian studies, this paper argues that the heretofore ways in which historians and philosophers of science have used the notion of “style” are severely restricted in terms of its mere applicability to the intellectual history of Western science. The particular example of the translation of “homosexuality” into Chinese during the May Fourth era reveals that the notion of “style” has the potential of carrying a much more dynamic conceptual weight, as when used in “styles of argumentation”. The paper also engages briefly with the historiography of scientific “national styles” and ends with some concluding remarks on the limitations of “social histories from below” and the under appreciated importance of “epistemological histories of possibilities”.     

Polymorphism and selection of rpoS in pathogenic Escherichia coli

Background  

Though RpoS is important for survival of pathogenic Escherichia coli in natural environments, polymorphism in the rpoS gene is common. However, the causes of this polymorphism and consequential physiological effects on gene expression in pathogenic strains are not fully understood.     

Age-related plumage differences of Dunlins along the East Asian-Australasian Flyway

ABSTRACT.   For some populations of Dunlins ( Calidris alpina ), determining the age of individuals on the nonbreeding grounds can be difficult. This difficulty arises in part because some populations undergo their primary molt during the boreal summer, leaving adult and first-year Dunlins with similar amounts of abrasion on their primaries. Ageing Dunlins is further complicated by the presence of adults with buff-fringed, inner median coverts in some populations, a feature often used to age juvenile Dunlins. We examined a number of characteristics helpful in the ageing Dunlins at nonbreeding areas along the East Asian-Australasian Flyway, including: (1) the pattern of white fringes on the inner primary coverts, (2) the color of fringes on the inner median wing coverts, (3) the color of the tip on the carpal covert, (4) the presence or absence of a dark subterminal band on tertial or tertial coverts, and (5) remnants of alternate or juvenile plumage on the belly. Our results demonstrate that the pattern of white fringes on the inner primary coverts is an important character for ageing Dunlin along the East Asian-Australasian Flyway. In addition, we found that all characteristics used for ageing fade with time, and that breeding adults along the East Asian-Australasian Flyway are more difficult to age than adults elsewhere, in part due to the presence of "adult buff" coverts (ABCs) and in part because of the early timing of primary molt. Finally, we suggest that the presence of ABCs might be useful for differentiating the two Dunlin subspecies ( C. a. arcticola and C. a. pacifica ) occurring in Alaska.