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411.
412.
Between January 1982 and December 1985, 65 species of Mollusca were collected from the Layari River, an ephemeral stream that bisects Karachi. Gastropods were dominant followed by bivalves. The upstream region is hypersaline and devoid of molluscs; the stretch within Karachi is heavily polluted and almost no living molluscs occur here. 相似文献
413.
Background
Poly(ADP-ribose) polymerase is evolutionarily conserved as a responder to various forms of stress. Though PARP's role in cell death is well addressed, its role in development and multicellularity is still an enigma. We have previously reported the role of PARP in oxidative stress induced delayed development of D. discoideum. 相似文献414.
Pragya Paramita Pal Sajeli A. Begum Ameer S. Basha Hiroshi Araya Yoshinori Fujimoto 《化学与生物多样性》2023,20(3):e202200840
Inhibiting nitric oxide (NO) or its production is found to be of therapeutic benefit. To discover natural small molecule inhibitors of NO production, a bioassay- and LC/MS-guided chemical investigation was done on the metabolites of endophytic fungus isolated from fresh Piper nigrum fruits. The isolated pure strain was identified as Penicillium polonicum by 16S rDNA sequence comparison. The culture broth extract of P. polonicum (EEPP) exhibited a significant reduction of NO production (Griess method) in LPS-stimulated RAW 264.7 cells (P<0.0001). To understand the chemical constituents of bioactive EEPP, column chromatography and p-TLC studies were carried out, which yielded eight pure compounds. They were characterised as botryosphaeridione ( 1 ), 3-(3,5-di-tert-butyl-4-hydroxy)phenylpropionic acid ( 2 ), variabilone ( 3 ), 2,4-di-tert-butylphenol ( 4 ), indole-3-carboxylic acid ( 5 ), tyrosol ( 6 ), ethyl ferulate ( 7 ) and a new lignan ( 8 ) based on the spectral analysis. The structure elucidation of the new lignan, named polonilignan ( 8 ), was based on HR-MS, 1H- & 13C-NMR, H−H COSY, HSQC and HMBC spectra. Compounds 2 , 4 , 5 and 6 showed a significant decrease (P<0.0001) in the production of NO in LPS-induced RAW 264.7 cells. Tyrosol ( 6 ) and indole-3-carboxylic acid ( 5 ) controlled nitrite release with IC50 values of 22.84 and 55.01 μM, respectively. This is the first report of (i) P. polonicum as an endophytic fungus of pepper fruits, (ii) isolation of compounds 1 – 8 except 6 from P. polonicum culture broth extract and (iii) NO inhibition effect of 2 , 4 , 5 and 6 . 相似文献
415.
Satoshi Nakaba Shahanara Begum Yusuke Yamagishi Hyun-O Jin Takafumi Kubo Ryo Funada 《Trees - Structure and Function》2012,26(3):743-750
Differences in the timing of cell death, differentiation and function among three different types of ray parenchyma cells
in the hardwood Populus sieboldii × P. grandidentata which form uniseriate and homocellular rays were examined and clarified. Ray parenchyma cells died within 5 years, and the
disappearance of nuclei from ray parenchyma cells did not occur successively from the pith side, even within individual radial
cell lines of a given ray. Cell death occurred earliest in contact cells, which were connected to adjacent vessel elements
through pits, in the fourth annual ring from the cambium. Cell death occurred next in intermediate cells, which were located
within the same cell lines as contact cells but were not adjacent to vessel elements, in the fourth annual ring from the cambium.
Finally, isolation cells, which were located within the other cell lines of a given ray, died in the fifth annual ring from
the cambium. Secondary wall thickenings in contact cells and intermediate cells were initiated before those in isolation cells
in the current year’s xylem. Most starch grains were localized in intermediate cells, and there were more lipid droplets in
contact cells and intermediate cells than in isolation cells. In addition, the largest quantities of protein were found in
contact cells. Our results indicate that the position within a ray and neighboring short-lived vessel elements might affect
the timing of cell death and differentiation and, thus, the function of long-lived ray parenchyma cells in Populus sieboldii × P. grandidentata. 相似文献
416.
Lina Nilsson Andreas Larsson Afshan Begum Irina Iakovleva Marcus Carlsson Kristoffer Br?nnstr?m A. Elisabeth Sauer-Eriksson Anders Olofsson 《PloS one》2016,11(4)
Amyloid formation of the plasma protein transthyretin (TTR) has been linked to familial amyloid polyneuropathy and senile systemic amyloidosis. Binding of ligands within its natural hormone binding site can stabilize the tetrameric structure and impair amyloid formation. We have recently shown that the flavonoid luteolin stabilizes TTR in human plasma with a very high selectivity. Luteolin, however, is inactivated in vivo via glucuronidation for which the preferred site is the hydroxy group at position 7 on its aromatic A-ring. We have evaluated the properties of two luteolin variants in which the 7-hydroxy group has been exchanged for a chlorine (7-Cl-Lut) or a methoxy group (7-MeO-Lut). Using an in vitro model, based on human liver microsomes, we verified that these modifications increase the persistence of the drug. Crystal structure determinations show that 7-Cl-Lut binds similarly to luteolin. The larger MeO substituent cannot be accommodated within the same space as the chlorine or hydroxy group and as a result 7-MeO-Lut binds in the opposite direction with the methoxy group in position 7 facing the solvent. Both 7-Cl-Lut and 7-MeO-Lut qualify as high-affinity binders, but in contrast to luteolin, they display a highly non-specific binding to other plasma components. The binding of the two conformations and the key-interactions to TTR are discussed in detail. Taken together, these results show a proof-of-concept that the persistence of luteolin towards enzymatic modification can be increased. We reveal two alternative high-affinity binding modes of luteolin to TTR and that modification in position 7 is restricted only to small substituents if the original orientation of luteolin should be preserved. In addition, the present work provides a general and convenient method to evaluate the efficacy of TTR-stabilizing drugs under conditions similar to an in vivo environment. 相似文献
417.
418.
Sathish Prasad Poorna Manasa Sailaja Buddhi Preethi Tirunagari Zareena Begum Sivaraman Rajan Sisinthy Shivaji 《Current microbiology》2014,68(2):233-238
The diversity and abundance of culturable bacteria in Kongsfjorden water (15 stations) and sediments (12 stations) were studied. Viable numbers ranged between 105–106 CFU l?1 in water and 102–104 CFU g?1 in the sediments. A total of 291 and 43 bacterial isolates were retrieved from the water (KJF) and sediments (FS), respectively. Based on 16S rRNA gene sequence similarities, the KJF and FS isolates were grouped into 49 and 23 phylotypes, respectively. The KJF and FS phylotypes represented three phyla namely, Actinobacteria, Bacteroidetes, and Proteobacteria. At the genus level, Flavobacterium and Shewanella and at the species level, Pseudoaltermonas arctica and Colwellia psychrerythraea were dominant in the water and sediments, respectively. Most phylotypes were psychrotolerant with upper growth temperature limit of 25–37 °C and tolerated 0.3–2.5 M NaCl and pH values of 5.0–11.0. Majority of the phylotypes produced one or more of the extracellular hydrolytic enzymes amylase, lipase, caseinase, urease, gelatinase, and DNase at 4 and 18 °C, while none were chitinolytic. Few of the FS phylotypes exhibited extracellular activity only at 4 or 18 °C. Nine FS and 21 KJF isolates were pigmented. The predominant cellular fatty acids were unsaturated, branched, and modified fatty acids, which are unique to cold-adapted bacteria. 相似文献
419.
420.
Shahanara Begum Satoshi Nakaba Yuichiro Oribe Takafumi Kubo Ryo Funada 《Trees - Structure and Function》2010,24(1):43-52
Differences in the timing of cambial reactivation and the initiation of xylem differentiation in response to the sum of daily
maximum temperatures were studied in two Cryptomeria japonica trees with cambium of different ages under natural and locally heated conditions. In addition, we observed the effects of
low temperature on cambial activity. The timing of cambial reactivation and of the initiation of xylem differentiation differed
between 55- and 80-year-old cambium under natural conditions. In the 55-year-old cambium, cambial reactivation occurred when
the cambial reactivation index (CRI), calculated on the basis of daily maximum temperatures in excess of 10°C, was 94 and
97°C in 2007 and 2008, respectively. In 80-year-old cambium, cambial reactivation occurred when the CRI, calculated on the
basis of daily maximum temperatures in excess of 11°C, was 69 and 71°C in 2007 and 2008, respectively. After cambial reactivation
in 2007, normal cell division was evident in the cambium even though the minimum temperature had fallen between −2 and −3°C.
Under natural conditions, xylem differentiation started 38–44 days after cambial reactivation. In heated stems, the time between
cambial reactivation and the initiation of xylem differentiation ranged from 14 to 16 days, a much shorter time than under
natural conditions, indicating that continuous exposure to an elevated temperature had induced earlier xylem differentiation.
Our observations indicate that the sensitivity to reactivation inducing stimuli of the cambium depends on both the stage of
dormancy and tree age of the cambium. 相似文献