Chemical composition of precipitation in a forest area of Chongqing,Southwest China

Experiments were carried.out in Chongging-a city seriously damaged by acid precipitation in southwest China — to explore chemical compositions of open bulk precipitation, throughfall and stemflow in a Masson pine (Pinus massoniana) forest. The results showed that annual mean pH values of and annual ion depositions in the three types of rain water were 4.47 and 50.6 g m^?2, 3.82 and 69.7 g m^?2, and 2.92 and 0.215 g m^?2 respectively. pH values demonstrated an obvious seasonal variation; they were lower in winter than in the rest of the year. Ca²⁺ and NH _inf4 ^sup+ together made up more than 80% of the total cation, while SO _in4 ^sup2? alone contributed over 90% to the total anion. This high level of SO _in4 ^sup2? in rain water in Chongqing, which outran those found in other cities in China, was closely related to the combustion of locally produced coal that contains 3 to 5% sulphur. Thus, acid precipitation in Chongqing is of a typical sulphuric-acid type.     

The Colletotrichum higginsianum secreted effector protein ChEC91 induces plant cell death

ChEC91, a novel cell death-inducing effector protein from the fungal pathogen Colletotrichum higginsianum, causal agent of crucifer anthracnose disease, is described. Both transient expression of ChEC91 and infiltration of purified recombinant protein induced necrotic lesions in Nicotiana benthamiana leaves. The recombinant protein also induced electrolyte leakage and callose deposition in Arabidopsis thaliana leaf tissue and the expression of defence marker genes. Moreover, fungal mutants constitutively over-expressing ChEC91 in C. higginsianum were impaired in appressorial penetration on Brassica rapa cotyledons. These results suggest that inappropriate expression of ChEC91 might negatively affect the early stage of C. higginsianum infection by inducing plant defence responses. Protein domain deletion analysis showed that the C-terminal region of ChEC91 was necessary, but not sufficient, for activity in N. benthamiana. Homologous effector proteins cloned from C. gloeosporioides, Fusarium graminearum, and Pyricularia oryzae differed in their cell death-inducing activity, which appeared related to sequence variations in the C-terminal region of these proteins. Moreover, this region contained amino acid residues that were well conserved within Colletotrichum species. These results suggest that the amino acid residues in the C-terminal region may be important for inducing cell death in plants.

     

The prevalence of antimicrobial-resistant Escherichia coli in two species of invasive alien mammals in Japan

The prevalence of antimicrobial resistance in 128 Escherichia coli isolates was investigated in two species of invasive alien mammals (IAMs): the small Asian mongoose (SAM) and Japanese weasel (JW). The SAM is found on the main island of Okinawa, Japan, where a large number of livestock is available, and the JW is present on a small island, where is isolated from the main island, and have a small number of livestock. We focused on the two IAMs, inhabiting under the different environments, and compared their prevalence of antimicrobial-resistant E. coli. In the comparison of the frequencies of antimicrobial-resistant E. coli isolates between the SAM and JW, JW showed significantly higher prevalence of resistance against three drugs, ampicillin, chlortetracycline and nalidixic acid, compared with SAM's test results (P<0.05). The bla(TEM) gene and the aph1 gene were detected in 35 subjects (91%) of ampicillin-resistant isolates and 6 subjects (100%) of kanamycin-resistant isolates, respectively. The tet (A) gene was detected in 62 subjects (46%) of CTC-resistant isolates, and the tet (B) gene was detected in 25 subjects (8%) of those in IAM. The present results suggest that some IAMs were the carrier of antimicrobial-resistant bacteria and their genes, and the frequencies of these resistances were different between two IAM species.     

Transcriptome analysis of the duodenum in Wistar rats fed a trypsin inhibitor derived from squid viscera

To investigate the effects of oral administration of a trypsin inhibitor (TI), normal Wistar rats were fed a TI derived from squid (Todarodes pacificus) for 10 weeks and gene expression profiles in the duodenum, pancreas, liver, and muscle were then analyzed using DNA microarrays. Although no significant changes could be observed in growth, food intake, tissue weight, or blood tests among the tissues tested, the duodenum showed the most remarkable changes in the global gene expression profile. Significant up-regulation of mRNAs encoding gastrin, gastrokine, cholecystokinin and somatostatin in the duodenum was validated by qPCR analysis. In gene ontology (GO) analysis of the up-regulated differentially expressed genes (DEGs), GO terms related to keratinization and innate mucosal defense were enriched (p < 0.001) in the category of biological processes in addition to assumable terms such as regulation of secretion and response to nutrients, vesicle-mediated transport, and so forth. In the same analysis, calcium ion binding was listed at the deepest hierarchy in the category of molecular function. These results indicate that the duodenum responds to TI treatment by a wider range of physiological processes than previously assumed such as keratinocyte differentiation and innate mucosal defense, in which calcium plays a crucial role.     

The biological activities of cardenolide triglycosides from stems, twigs, and leaves of Nerium oleander

Sixteen cardenolide triglycosides (1?C16) were isolated from stems, twigs, and leaves of Nerium oleander. Among them, 3??-O-(4-O-gentiobiosyl-d-diginosyl)-7??,8-epoxy-14-hydroxy-5??,14??-card-20(22)-enolide, named cardenolide B-3 (16), was isolated from natural sources for the first time. The in vitro anti-inflammatory activities of compounds 1?C16 were examined on the basis of inhibitory activity against the induction of intercellular adhesion molecule-1 (ICAM-1). Compounds 1?C5 were active at an IC50 value of less than 7 ??M. The cytotoxic activity of isolated compounds was evaluated against three human cell lines: normal human fibroblast cells (W-38), malignant tumor cells induced from WI-38 (VA-13), and human liver tumor cells (HepG2). Compounds 1?C5 were active toward WI-38 cells; compounds 1, 3, and 5 were active toward VA-13 cells; and compounds 1?C5 were active toward HepG2 cells at IC₅₀ values of less than 10 ??M. The multidrug-resistant (MDR) cancer-reversal activity of compounds 1?C16 was evaluated on the basis of the amount of calcein accumulated in MDR human ovarian cancer 2780AD cells in the presence of each compound. Compounds 13 and 14 showed significant effects on calcein accumulation.     

Evaluation of nitrogen status of agricultural soils in Java,Indonesia

Abstract

To evaluate the content of nitrogen (N) fractions of agricultural soils in Java, Indonesia, in relation to soil type and land use, 46 surface soil samples, 23 from paddy and 23 from upland, were collected throughout Java to include various types of soils. Soil N was separated into four fractions according to form and availability: inorganic extractable nitrogen (Iex-N), fixed ammonium nitrogen (Ifix-N), organic mineralizable nitrogen (Omin-N) and organic stable nitrogen (Osta-N). The total-N content was determined by the dry combustion method. The Iex-N content was determined by extraction with a 2 mol L^?1 potassium chloride (KCl) solution and the Ifix-N content by extraction with an hydrofluoric and hydrochloric acid (HF-HCl) solution after removal of organic-N. The Omin-N content was evaluated as the potentially mineralizable N based on a long-term incubation method. The Osta-N content was calculated as the difference between the contents of total-N and the three other fractions. The total-N content was 2.06 g kg^?1 on average. The contents of Iex-N, Ifix-N, Omin-N and Osta-N were 25.8, 99.1, 103 and 1,832 mg kg^?1, respectively, and corresponded to 1.3, 4.8, 5.0 and 88.9% of the total-N. Hence, available (Iex-N and Omin-N) and stable (Ifix-N and Osta-N) fractions accounted for 6.3% and 93.7% of the total-N, respectively. Correlation analysis indicated that the contents of total-N and Osta-N had positive correlation with (Alo + 1/2Feo) as an index of amorphous minerals (p < 0.01), suggesting strong influence of volcanic materials for the accumulation of organic matter in Java soils. The content of Ifix-N had a positive correlation with nonexchangeable potassium (K) content (p < 0.01), suggesting the contribution of 2:1 clay minerals which can fix both ammonium (NH₄⁺) and K⁺ in their interlayer sites. On the contrary, Omin-N did not have any significant correlation with soil properties, implying the importance of management for the improvement of the available N level in soils, rather than intrinsic soil properties. Soil N status further showed strong topographical trends depending on the elevation where soil developed. The contents of total N, Iex-N, Ifix-N, Omin-N and Osta-N in Java soils were on average 80, 69, 90, 65 and 80% of those in Japanese soils, respectively, suggesting that the soil N level in Java was lower than that in Japan, probably due to accelerated decomposition of organic matter, especially degradable fractions, reflecting high temperature, but that the level was relatively high for tropical soils due to the effect of volcanic materials. In conclusion, these results should be taken into account for the sustainable management of soil N in agricultural fields in Java, Indonesia.     

Improved waterlogging tolerance of barley (Hordeum vulgare) by pretreatment with ethephon

ABSTRACT

Root growth into hypoxic or anoxic waterlogged soil relies on internal aeration in plants. The plant hormone ethylene helps adapt to waterlogging by inducing the formation of aerenchyma, which provides a low-resistance pathway for the transport of oxygen from the shoot to the root apex. Waterlogging-susceptible crops including barley start to form aerenchyma after suffering waterlogging stress. But waterlogging can be fatal if aerenchyma formation is not fast enough. Here, we investigated whether pre-treating barley with ethephon, an ethylene-releasing agrochemical, could improve its tolerance to mimicked waterlogging conditions (using stagnant deoxygenated agar nutrient solution). In barley growing in aerated nutrient solution, ethephon treatment enhanced aerenchyma formation at the root tips and induced the development of shorter and shallower roots. Pre-treating barley leaves also delayed waterlogging-caused whiting and increased the percentages of viable root-tips under waterlogging conditions. However, the pretreatment did not noticeably increase fresh weight or shoot length. Further studies are needed to optimize ethephon treatment conditions to improve barley production under waterlogged conditions.