Relationships between force curves and muscle oxygenation kinetics during repeated handgrip

The purpose of this study was to clarify the kinetics of muscle oxygenation by near infrared spectroscopy (NIRS) in the phase of the decreasing force, especially the pre- and post-phases of the inflection point, during repeated rhythmic grip (RRG) of 30 grips/min(-1) for 6 minutes. The inflection point was the time at which the decreasing speed of the grip force changed markedly. It was calculated statistically from two regression lines fitted to each decreasing phase by applying a two-phase regression model. Ten healthy males performed the RRG for 6 minutes. Total Hb and Oxy-Hb decreased rapidly about 10 sec (7.0+/-5.9 sec, 9.8+/-5.4 sec, respectively) corresponding to the value decreasing by 90% MVC after the onset of gripping. Deoxy-Hb was maintained at a high value for 76.2+/-27.9 sec, corresponding to the value decreasing by 70-80% MVC. These phases are considered to be the states where oxygen was not satisfactorily supplied to the active muscles because of the obstruction of blood flow caused by an increase in the intra-muscular pressure. Deoxy-Hb decreased for 120+/-21.3 sec after reaching the highest value, and then reached an almost steady state at a higher level than the rest. After this phase, muscle oxygenation kinetics enters the state where oxygen is satisfactorily supplied to active muscles. We considered that the relationship between oxygen supply and demand differs during the initial and the latter phases in RRG. The changing phase in the decreasing speed of the grip force, namely the inflection point of the decreasing force, significantly correlated with the changing phase of the Oxy-Hb and Deoxy-Hb kinetics. The inflection point of the decreasing force seems to correspond to the phase where oxygen supply cannot meet oxygen demand and the increase of Deoxy-Hb. We infer that the pre- and post-phases of the inflection point depend on different physiological factors.     

Immunological identification of crustacean androgenic gland hormone, a glycopeptide

Androgenic gland hormone (AGH) is known to be responsible for sex differentiation in crustaceans. The amino acid sequence of AGH-active fraction purified from androgenic glands of the terrestrial isopod Armadillidium vulgare was determined by immunoprecipitation employing three types of antibodies raised against differing parts of the amino acid sequence deduced from the putative AGH cDNA sequence. As all antibodies adsorbed AGH activity, it was confirmed that the sequence examined was that of AGH. The affinity of AGH to certain lectins indicated that AGH possesses a carbohydrate moiety, which is in agreement with the observation that AGH possesses an N-glycosylation consensus sequence.     

Expression of canine interferon-beta by a recombinant vaccinia virus

A recombinant vaccinia virus expressing canine interferon (IFN)-beta was constructed (vv/cIFN-beta). In rabbit kidney (RK13) and canine A72 cells infected with vv/cIFN-beta, the recombinant canine IFN-beta was detected in both cell extracts and supernatants, and the IFN activities of the culture supernatants were also detected. Inhibition of N-linked glycosylation by tunicamycin treatment indicated that the recombinant canine IFN-beta was modified by N-linked glycosylation in a different way between RK13 and A72 cells, and that N-linked glycosylation is essential for its secretion. The growth of vv/cIFN-beta at a low multiplicity of infection was inhibited by antiviral activity of canine IFN-beta, indicating that this recombinant virus could be used as a suicide viral vector.     

Monoclonal antibody inhibition of Neospora caninum tachyzoite invasion into host cells

Monoclonal antibodies were produced against Neospora caninum tachyzoites to identify antigens which may play a role during invasion of host cells. Confocal laser microscopy showed that most antigens recognised by the mAb were located on the surface, but one mAb, 1A5, reacted to the apical end of the parasite. Some mAbs, which recognised 70, 42 and 36kDa parasite proteins, significantly inhibited the invasion of the parasite in vitro. The mAbs which recognised 42 and 36kDa parasite protein, reacted with Nc-p43 and Nc-p36 expressed by vaccinia virus and Escherichia coli, respectively. These results suggest that a 70kDa protein, Nc-p43 and Nc-p36 are involved in the invasion of the parasite into host cells.     

Gordonan, an acidic polysaccharide with cell aggregation-inducing activity in insect BM-N4 cells, produced by Gordonia sp

An acidic polysaccharide, termed gordonan, was isolated from the culture medium of Gordonia sp. as an inducer of cell aggregation in an insect cell line, BM-N4. Gordonan had an average molecular weight of 5 x 10(6) and its structure was identified as -->3)-4-O-(1-carboxyethyl)-beta-D-Manp-(1-->4)-beta-D-GlcAp-(1-->4)-beta-D-Glcp-(1--> mainly by acid hydrolysis experiments and NMR analysis. It induces cell aggregation at the concentration of 4 microg/ml. A partially hydrolyzed polysaccharide derived from gordonan with a molecular weight of 5 x 10(5) showed weak activity, while any fragment molecules with lower molecular weights prepared from gordonan showed no activity.     

Habituation by a tortoise beetle to the deterrents of spinach

Abstract:  Feeding responses of Cassida nebulosa to spinach vary depending on prior dietary experience. Adults reared on spinach, eat much spinach whereas those reared on Chenopodium album var. centrorubrum rarely eat it. However, there are a few reports that address the mechanisms of this phenomenon, which is termed 'induction of preference'. It has been presumed that this phenomenon arises in response to a reduction of sensitivity to the feeding deterrents contained in spinach as a result of early experience feeding on it. Therefore, we attempted to verify the effects of the feeding deterrent that was isolated from spinach. The feeding-deterrent response was reduced in adults reared on spinach compared with adults reared on C. album var. centrorubrum . Additionally, consumption of spinach by adults reared on deterrent-treated leaves of C. album var. centrorubrum was significantly higher than that by adults reared on control leaves of C. album var. centrorubrum . These results indicate that C. nebulosa acquires the ability to tolerate spinach because sensitivity to the feeding deterrent contained in spinach is reduced by early experience with the deterrent.     

Identification of mycobionts in an achlorophyllous orchid,Cremastra aphylla (Orchidaceae), based on molecular analysis and basidioma morphology

Mycorrhizal fungi were isolated and cultured from rhizomes of mycoheterotrophic Cremastra aphylla (Orchidaceae) plants collected in 3 sites across Japan. In total, 5 Cr. aphylla individuals were collected, and 10 fungal isolates were obtained. Sequence analysis of the internal transcribed spacer regions (ITS) of nuclear ribosomal DNA from the fungal samples revealed that all isolates belonged to the genus Coprinellus in the family Psathyrellaceae. All isolates from each site were of the same phylotype. In total, 3 ITS phylotypes were detected. One of the isolates produced fruiting bodies and was identified as Co. domesticus on the basis of macro- and microscopic characteristics of the basidiomata and ITS sequence data. In this study, the sharing of saprobic Psathyrellaceae fungus by the mycoheterotrophic and leafy Cremastra species was newly confirmed.     

Quantification and localization of erythropoietin-receptor-expressing cells in the liver of Xenopus laevis

Erythropoiesis occurs in the African clawed frog, Xenopus laevis and is mediated by erythropoietin (xlEPO), a primary regulator of this process. Previously, we have shown that the xlEPO receptor (xlEPOR), which is expressed by erythroid progenitors that respond to xlEPO, is found predominantly in the liver. The aim of the present study was to determine the dynamics of erythropoiesis in the livers of normal and anemic X. laevis by identifying the number and precise location of mature and immature erythrocytes. We quantified mature and immature erythrocyte numbers by o-dianisidine staining or immunohistochemistry and investigated the dynamics of erythropoiesis in normal, acute hemolytic and blood-loss states by in vivo cell proliferation assays with 5-bromo-2′-deoxyuridine (BrdU). We detected 0.12×10⁸ xlEPOR⁺ BrdU⁺ cells in the liver of the normal X. laevis at 24 h after BrdU injection. Frogs presenting with acute hemolytic anemia and pancytopenia show a 10-fold increase in the number of xlEPOR⁺/BrdU⁺ cells (approximately 1.30×10⁸ cells) in the liver. The xlEPOR⁺ cells are found predominantly on the inner wall of hepatic sinusoids. Hematopoietic progenitors that undergo slow cell cycling were also observed in the hepatic sinusoids. This study clarifies the rate of production of mature and immature erythrocytes per day in the liver of X. laevis and the way that these cell numbers change in response to anemia.     

Modifying the LEACHM model for process-based prediction of nitrate leaching from cropped Andosols

Aims

Nitrogen (N) management strategies for reducing the risk of groundwater contamination around agricultural fields require precise prediction of N leaching using a process-based model. We modified LEACHM model for use in Andosols, which are characterized by slow soil organic carbon (SOC) mineralization and nitrate adsorption.

Methods

The modification was made with regard to the SOC mineralization of incoming plant-residue/manure and humus following the RothC model, as well as for nitrate adsorption. Empirical equations were employed to determine the parameters of the modified model. The ability of the modified LEACHM to predict N leaching was tested against existing data from a 4-year lysimeter study for cropped Andosol and sandy soils and compared with that of the original model.

Results

The modified model improved the prediction of leached N concentrations and the loss of N from Andosol with relative improvements of 63.5 and 76.5 %, respectively, over the original model, while retaining model applicability in sandy soil. This effective modeling was achieved by using precise predictions of N mineralization in the humus pool along with SOC mineralization processes that were based on the RothC model.

Conclusions

The modification extended the applicability of LEACHM and may provide better N management strategies for reducing leaching from cultivated Andosols.     

Genetic variation among natural isolates of the ectomycorrhizal hypogenous fungus,Rhizopogon roseolus from Japanese pine forests inferred using AFLP markers

Genetic variation among 45 Rhizopogon roseolus isolates from 21 different regions of Japan were inferred using amplified fragment length polymorphism (AFLP) markers. Using three primer pair combinations, AFLP analysis reproducibly produced a total of 223 DNA fragments, 74.4% of which were polymorphic. Pairwise dissimilarity of AFLP patterns between isolates ranged from 0.043 to 0.228. Cluster analysis and principal coordinate analysis of AFLP data generally showed four major clusters from geographically distinct areas. The findings suggested that the Japanese populations of R. roseolus from different geographical regions can be distinguished based on AFLP characters.