Individual food niche specialization in stream-dwelling charr

Food niche variation within a population of white-spotted charr, Salvelinus leucomaenis, was investigated by means of mark and recapture to examine the simplification that conspecific individuals are ecologically equivalent. Food diversity measured on the basis of living form of dietary organisms demonstrated variability in food niche in incidence, degree, and stability. As inferred from body size distribution and fish movement, niche variation was inexplicable by social rank hierarchy or foraging habitat rotation, and occasional niches were deemed to be realized individually. Higher annual growth rate shown by those with a larger niche width indicated the adaptive significance in niche variation. Assuming trade-off between feeding efficiency and predation risk, phenotypic plasticity was suggested to determine the food niche specialization of individuals to maximize lifetime fitness.     

Mating system and mate choice of Tengmalm's Owls Aegolius funereus

The mating system and mate choice of Tengmalm's Owls were studied in relation to population fluctuations of the staple food (voles) for seven years in western Finland. Three age classes of owls were differentiated: first-year, second-year and older owls. Despite a surplus of males, 11 % of them showed simultaneous bigyny in peak vole years. The mean distance between primary and secondary nests was 1158 m, and usually there was a free nest-box between the two nests. Because primary nests produced more fledglings than secondary ones and secondary nests produced fewer fledglings than simultaneous or even eight-days-later monogamous nests, this bigyny could be best explained by the 'deception' hypothesis.
In successive biandry, females deserted their first brood when young were still in the nest, thereby transferring the burden of raising the young to their males. The tendency of assortative mating by age (more yearling x yearling and + 2-year-old ×+ 2-year-old pairs than expected by chance) showed that females chose older males when these were available.     

Combined Cell Surface Display of β‐d‐Glucosidase (BGL), Maltose Transporter (MAL11), and Overexpression of Cytosolic Xylose Reductase (XR) in Saccharomyces cerevisiae Enhance Cellobiose/Xylose Coutilization for Xylitol Bioproduction from Lignocellulosic Biomass

Xylitol is a highly valuable commodity chemical used extensively in the food and pharmaceutical industries. The production of xylitol from d ‐xylose involves a costly and polluting catalytic hydrogenation process. Biotechnological production from lignocellulosic biomass by micro‐organisms like yeasts is a promising option. In this study, xylitol is produced from lignocellulosic biomass by a recombinant strain of Saccharomyces cerevisiae (S. cerevisiae) (YPH499‐SsXR‐AaBGL) expressing cytosolic xylose reductase (Scheffersomyces stipitis xylose reductase [SsXR]), along with a β‐d ‐glucosidase (Aspergillus aculeatus β‐glucosidase 1 [AaBGL]) displayed on the cell surface. The simultaneous cofermentation of cellobiose/xylose by this strain leads to an ≈2.5‐fold increase in Yxylitol/xylose (=0.54) compared to the use of a glucose/xylose mixture as a substrate. Further improvement in the xylose uptake by the cell is achieved by a broad evaluation of several homologous and heterologous transporters. Homologous maltose transporter (ScMAL11) shows the best performance in xylose transport and is used to generate the strain YPH499‐XR‐ScMAL11‐BGL with a significantly improved xylitol production capacity from cellobiose/xylose coutilization. This report constitutes a promising proof of concept to further scale up the biorefinery industrial production of xylitol from lignocellulose by combining cell surface and metabolic engineering in S. cerevisiae.     

Characterization of enzymes involved in the ethanol production of <Emphasis Type="Italic">Moorella</Emphasis> sp. HUC22-1

Since the thermophilic bacterium Moorella sp. HUC22-1 produces 120 mM acetate and 5.2 mM ethanol from H₂–CO₂, several candidate genes, which were predicted to code for three alcohol dehydrogenases (AdhA, B, C) and one acetaldehyde dehydrogenase (Aldh), were cloned from HUC22-1. The cloned genes were subcloned into a His-tagged expression vector and expressed in Escherichia coli. Recombinant AdhA and B were both dependent on NADP(H) but independent of NAD(H), and their reduction activities from aldehyde to alcohol were higher than their oxidation activities. In contrast with AdhA and B, no activity of AdhC was observed in either reaction. On the other hand, Aldh was active toward both NADP(H) and NAD(H). The enzyme activity of Aldh was directed toward the thioester cleavage and the thioester condensation. When 50 μg of AdhA and 50 μg Aldh were added to the buffer solution (pH 8.0) containing NADPH, NADH and acetyl-CoA at 60°C, 1.6 mM ethanol was produced from 3 mM acetyl-CoA after 90 min. Expression analysis of the mRNAs revealed that the expression level of aldh was threefold higher in the H₂–CO₂ culture than that in the fructose culture, but levels of adhA, B and C were decreased.     

Description of a New Planktonic Mixotrophic Dinoflagellate Paragymnodinium shiwhaense n. gen., n. sp. from the Coastal Waters off Western Korea: Morphology,Pigments, and Ribosomal DNA Gene Sequence

ABSTRACT. The mixotrophic dinoflagellate Paragymnodinium shiwhaense n. gen., n. sp. is described from living cells and from cells prepared by light, scanning electron, and transmission electron microscopy. In addition, sequences of the small subunit (SSU) and large subunit (LSU) rDNA and photosynthetic pigments are reported. The episome is conical, while the hyposome is hemispherical. Cells are covered with polygonal amphiesmal vesicles arranged in 16 rows and containing a very thin plate‐like component. There is neither an apical groove nor apical line of narrow plates. Instead, there is a sulcal extension‐like furrow. The cingulum is as wide as 0.2–0.3 × cell length and displaced by 0.2–0.3 × cell length. Cell length and width of live cells fed Amphidinium carterae were 8.4–19.3 and 6.1–16.0 μm, respectively. Paragymnodinium shiwhaense does not have a nuclear envelope chamber nor a nuclear fibrous connective (NFC). Cells contain chloroplasts, nematocysts, trichocysts, and peduncle, though eyespots, pyrenoids, and pusules are absent. The main accessory pigment is peridinin. The sequence of the SSU rDNA of this dinoflagellate (GenBank AM408889) is 4% different from that of Gymnodinium aureolum, Lepidodinium viride, and Gymnodinium catenatum, the three closest species, while the LSU rDNA was 17–18% different from that of G. catenatum, Lepidodinium chlorophorum, and Gymnodinium nolleri. The phylogenetic trees show that this dinoflagellate belongs within the Gymnodinium sensu stricto clade. However, in contrast to Gymnodinium spp., cells lack nuclear envelope chambers, NFC, and an apical groove. Unlike Polykrikos spp., which have a taeniocyst–nematocyst complex, P. shiwhaense has nematocysts without taeniocysts. In addition, P. shiwhaense does not have ocelloids in contrast to Warnowia spp. and Nematodinium spp. Therefore, based on morphological and molecular analyses, we suggest that this taxon is a new species, also within a new genus.     

APPLIED ISSUES: Effects of habitat rehabilitation on brown trout (Salmo trutta) in boreal forest streams

1. Degradation of stream habitat because of anthropogenic activities (e.g. channelisation) has had a dramatic impact on fluvial environments and their biota, and as a consequence, increasing effort has been directed towards the restoration of degraded rivers. However, a major problem is that the success (or failure) of restoration has been rarely tested using a well‐designed monitoring programme to allow reliable detection of an impact, if any exists. We used a spatially and temporally replicated, balanced Before‐After‐Control‐Impact design to assess the impact of stream habitat rehabilitation on the densities and growth of brown trout of three age‐classes in North Finnish forest streams. 2. Three separate sections in each of six streams were selected for the study. After 3 years of pre‐rehabilitation monitoring, two randomly selected sections in each stream were restored; one using large woody debris and boulders and the other using only boulders. A third section remained as an unmodified control. Monitoring of fish densities continued for 3 years after rehabilitation. 3. Rehabilitation clearly increased streambed complexity, but did not have detectable effects on brown trout stocks in either of the rehabilitation schemes (LWD or stones), except for age‐2+ and older fish which decreased in abundance compared to control reaches. A severe drought after rehabilitation in late summer 2002 reduced densities of trout to a low level in all streams, overriding any local effects of rehabilitation. Rehabilitation structures seemed to provide some safeguard against drought for age‐2 and older, but not for the younger age‐classes. 4. Our results add to the growing body of literature suggesting that large‐scale regional factors may overwhelm local management efforts. To be successful in the future, stream rehabilitation schemes must include drought refuge areas for fish and other stream biota.     

Ixodid tick species recovered from domestic dogs in Japan

The species of ixodid ticks (Acari: Ixodidae) recovered from domestic dogs in Japan between September to November 2000 and April to June 2001 were identified. A total of 4122 ticks, including 1624 larvae, 1200 nymphs, 1016 females and 282 males were removed from 1221 dogs during these periods. Haemaphysalis longicornis (Neumann) was the most frequently found (40.3% of dogs), followed by H. flava (Neumann) (16.1% of dogs), Rhipicephalus sanguineus (Latreille) (4.8% of dogs) and Ixodes ovatus (Neumann) (4.1% of dogs). Small numbers of H. hystricis (Supino), H. campanulata (Warburton), H. japonica (Warburton), H. ias (Nakamura and Yajima), I. persulcatus (Schulze), I. nipponensis (Kitaoka and Saito) and Amblyomma testudinarium (Koch) were also recovered. In the spring sample, a total of 1408 ticks (78 larvae, 411 nymphs, 792 adult females and 127 adult males) were recovered from 570 dogs. The autumn sample included a larger proportion of larval stage and fewer adult ticks (1546 larvae, 789 nymphs, 224 adult females and 155 adult males). Haemaphysalis longicornis, H. flava and I. ovatus showed a wide geographical distribution from northern to southern Japan, whereas R. sanguineus were mainly distributed in the subtropical Okinawa prefecture with a few exceptions. Dogs in rural areas more frequently carried H. longicornis, H. flava and I. ovatus than dogs in urban or suburban areas, whereas R. sanguineus was more associated with the dogs in urban/suburban areas. Exposure to a garden was significantly associated with R. sanguineus and exposure to woodland was significantly associated with H. flava and I. ovatus. This is the first systematic survey of canine ticks in Japan.