Using degenerate polymerase chain reaction (PCR) and thermal asymmetric interlaced PCR, a 1,347-bp full-length complementary DNA fragment encompassing the gene man5A, which encodes a 429-amino acid beta-mannanase with a calculated mass of 46.8 kDa, was cloned from acidophilic Bispora sp. MEY-1. The deduced amino acid sequence (catalytic domain) displayed highest identity (54.1%) with the Emericella nidulans endo-beta-1,4-D-mannanase, a member of the glycoside hydrolase family 5. Recombinant MAN5A was overexpressed in Pichia pastoris, and its activity in the culture medium reached 500 U ml(-1). The enzyme was acidophilic, with highest activity at pH 1.0-1.5, lower than any known mannanases, and optimal temperature for activity was 65 degrees C. MAN5A had good pH adaptability, excellent thermal and pH stability, and high resistance to both pepsin and trypsin. The specific activity, K(m), and V(max) for locust bean gum substrate was 3,373 U mg(-1), 1.56 mg ml(-1), and 6,587.6 micromol min(-1) mg(-1), respectively. The enzymatic activity was not significantly affected by ions such as Ca(2+), Cr(3+), Co(2+), Zn(2+), Na(+), K(+), and Mg(2+) and enhanced by Ni(2+), Fe(3+), Mn(2+) and Ag(+). These favorable properties make MAN5A a potential candidate for use in various industrial applications.

A complete gene, xyl10C, encoding a thermophilic endo-1,4-beta-xylanase (XYL10C), was cloned from the acidophilic fungus Bispora sp. MEY-1 and expressed in Pichia pastoris. XYL10C shares highest nucleotide and amino acid sequence identities of 57.3 and 49.7%, respectively, with a putative xylanase from Aspergillus fumigatus Af293 of glycoside hydrolase family 10. A high expression level in P. pastoris (73,400 U ml(-1)) was achieved in a 3.7-l fermenter. The purified recombinant XYL10C was thermophilic, exhibiting maximum activity at 85 degrees C, which is higher than that reported from any fungal xylanase. The enzyme was also highly thermostable, exhibiting approximately 100% of the initial activity after incubation at 80 degrees C for 60 min and >87% of activity at 90 degrees C for 10 min. The half lives of XYL10C at 80 and 85 degrees C were approximately 45 and 3 h, respectively. It had two activity peaks at pH 3.0 and 4.5-5.0 (maximum), respectively, and was very acid stable, retaining more than 80% activity after incubation at pH 1.5-6.0 for 1 h. The enzyme was resistant to Co(2+), Mn(2+), Cr(3+) and Ag(+). The specific activity of XYL10C for oat spelt xylan was 18,831 U mg(-1). It also had wide substrate specificity and produced simple products (65.1% xylose, 25.0% xylobiose and 9.9% xylan polymer) from oat spelt xylan.

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A genic male sterile Chinese cabbage, Brassica campestris L. ssp. chinensis Makino, was examined using cytological and cytochemical methods to characterize the process of pollen abortion in this plant. Thick sections of both fertile and sterile anthers at different developmental stages were stained using Toluidine Blue O, Periodic Acid-Schiff's (PAS) reaction and Sudan Black B to detect cytochemical changes that may occur in the distribution of insoluble polysaccharide and lipid storage bodies. Pollen abortion in sterile anthers occurs at an early stage of microspore development. During early microspore development, reductions in the number of starch grains in the connective tissue of fertile anthers coincide with the accumulation of starch grains in cells of the anther wall. In the late microspore stage, a large vacuole forms in the microspore, and tapetal cells synthesize and accumulate lipid droplets. The cellular organization of tapetal cells in sterile anthers appears similar to that in fertile anthers, except for the absence of lipid droplets in cells of sterile anthers and diffusely labeled tapetal polysaccharides, suggesting defects in nutrient storage.

Aluminum (Al)-tolerance of different cultivars shows considerable differences. Elevation of rhizosphere pH is an external Al-resistant mechanism of plants. To elucidate the correlation between Al tolerance and the capacity of plants to modify the rhizosphere pH at different Al-tolerant levels, a comparative study on the wheat (Triticum aestivum L.) cultivars ET8 (Al-tolerant) and ES8 (Al-sensitive) was performed. Rhizosphere pH of ET8 was much higher than that of ES8 under the same treatment, significant correlations were obtained among all the data of rhizosphere pH and relative root elongation (R² = 0.9209**), or Al content in root apex (R²= 0.9321**), which indicated that Al tolerance may be related to pH changes in the rhizosphere. The elevation of rhizosphere pH was inhibited by H⁺-ATPase specific inhibitor DCCD (dicylcohexylcarbodiimide, 25 mmol). Relative PM (plasma membrane) H⁺-ATPase activity of ET8 was significantly higher than that of ES8 under the same treatment. Significant correlation between all the data of relative PM H⁺-ATPase activity and rhizosphere pH (R² = 0.8319**) were obtained. Taken together, these results suggest that PM H⁺-ATPase was involved in regulating rhizosphere pH. Under Al stress, the Al-tolerant line showed a stronger capacity of up-regulating rhizosphere pH by PM H+-ATPase than the Al-sensitive line, which may explain the observed differences in Al tolerance between the two wheat cultivars.

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BackgroundStudies have identified mutations in >50 genes that can lead to monogenic steroid-resistant nephrotic syndrome (SRNS). The NUP160 gene, which encodes one of the protein components of the nuclear pore complex nucleoporin 160 kD (Nup160), is expressed in both human and mouse kidney cells. Knockdown of NUP160 impairs mouse podocytes in cell culture. Recently, siblings with SRNS and proteinuria in a nonconsanguineous family were found to carry compound-heterozygous mutations in NUP160.MethodsWe identified NUP160 mutations by whole-exome and Sanger sequencing of genomic DNA from a young girl with familial SRNS and FSGS who did not carry mutations in other genes known to be associated with SRNS. We performed in vivo functional validation studies on the NUP160 mutations using a Drosophila model.ResultsWe identified two compound-heterozygous NUP160 mutations, NUP160R1173× and NUP160E803K. We showed that silencing of Drosophila NUP160 specifically in nephrocytes (fly renal cells) led to functional abnormalities, reduced cell size and nuclear volume, and disorganized nuclear membrane structure. These defects were completely rescued by expression of the wild-type human NUP160 gene in nephrocytes. By contrast, expression of the NUP160 mutant allele NUP160R1173× completely failed to rescue nephrocyte phenotypes, and mutant allele NUP160E803K rescued only nuclear pore complex and nuclear lamin localization defects.ConclusionsMutations in NUP160 are implicated in SRNS. Our findings indicate that NUP160 should be included in the SRNS diagnostic gene panel to identify additional patients with SRNS and homozygous or compound-heterozygous NUP160 mutations and further strengthen the evidence that NUP160 mutations can cause SRNS.