Impact of rapid urbanization on the floral diversity and agriculture land of district Dir,Pakistan

In the World urbanization is a serious problem especially in developing countries which creates serious environmental problems like climatic and ecological changes in the ecosystem. The present paper aims to explain urbanization that causes loss of agriculture lands, biodiversity, soil erosions and grazing in District Dir. Urbanization decreased species richness such as Salix alba and Populus alba in the last few years in the local area. Soil of local area was divided into three different zones and was tested for soil texture and mineral percentage. Zone I soil showed sandy loamy texture with a pH of 8.3, Nitrogen 0.012%, Phosphorus 5.0% and organic matter was 0.74 (ppm). Zone II soil was loamy sand in texture with pH 8.1, Nitrogen 0.011%, Phosphorus 6.2%, and organic matter was 0.24 (ppm) while Zone III soil texture was silty clay loam with a pH of 8.1, Nitrogen 0.032%, Phosphorus 11.3%, and organic matter was 0.60 (ppm). The current work concludes that urbanizations affect natural biodiversity and agriculture lands, and that soil erosion and watering-points trampled by livestock is one of the significant problems in district Dir, and that the main degrading factor is the overexploitation of vegetation for fuel-wood and livestock grazing.     

Effect of dietary selenium, zinc and allopurinol supplements on plasma and tissue manganese levels in rats with thiocetamide-induced liver cirrhosis

The effect of thiocetamide-induced liver cirrhosis on plasma and tissuemanganese levels and the protective role of selenium, zinc and allopurinolsupplements was investigated in rats. Control plasma and liver manganese(Mn) levels were found to be (mean ± SD): 8.4 ± 2.4 mg/L and5.7 ± 1.5 mg/g wet weight respectively. Plasma manganese levels weresignificantly increased (p < 0.001) whereas liver manganese levels weresignificantly reduced (p < 0.05) in the cirrhotic rats. Treatment withselenium, zinc and allopurinol reversed this trend and restored themanganese levels close to the normal values. Lung, spleen, and kidneymanganese levels under control conditions were considerably lower than thatof the liver tissue. However, these levels registered a significant increase(p < 0.05) in cirrhotic rats and this change was normalized after selenium,zinc and allopurinol treatment. There were no significant differences in thecomparative efficacy of each of these protective agents. Zinc supplementconsiderably increased the plasma zinc levels and plasma Zn/Mn ratio had agood correlation with plasma zinc concentration. This ratio wassignificantly reduced in cirrhotic rats, but returned to the control levelafter zinc, selenium and allopurinol treatment. The results of this studyindicate that the trace element, manganese, plays an important role instabilizing cell structure and that this effect is mediated possibly bypreserving the antioxidant activity of the tissues.     

Development of a ploidy series from a single interspecific Trifolium repens L.Ā . nigrescens Viv. F1 hybrid

 The objective of the current research was to generate a ploidy series of backcross progenies from a single triploid (2n=3x=24) Trifolium repens×T. nigrescens F₁ hybrid (3x H-6909-5). The 3x H-6909-5 plant was highly sterile and produced no seeds from approximately 3000 reciprocal backcrosses to both parental species. Chromosome doubling by an in vitro colchicine method resulted in a marked increase in fertility. Pollen stainability was increased from 9.9% in 3x H-6909-5 to an average of 89.2% (range 87.7–90.9%) in the three chromosome-doubled 6x H-6909-5 plants. Subsequent backcrosses of 6x H-6909-5 and interbreeding of backcross derivatives resulted in an array of fertile hybrids at 4x, 5x and 7x levels and some aneuploids. The occurrence of 7x BC₁F₁ progeny from the T. repens×6x H-6909-5 (4x×6x) cross is the first unequivocal evidence of functional female 2n gametes in white clover. Meiotic pairing in F₁ and BC₁F₁ progeny indicated the presence of allosyndetic pairing, suggesting that genetic exchange between the two species is possible. Received: 17 October 1996 / Accepted: 8 November 1996     

Exposure of Escherichia colito acid habituation conditions sensitizes it to alkaline stress

R.J. ROWBURY AND N.H. HUSSAIN. 1996. Escherichia coli transferred from pH 7.0 to pH 5.5 or 6.0 became alkali-sensitive by a rapidly induced phenotypic response. Alkali sensitization was reduced at pH 5.0 and virtually abolished at pH 6.5. The response was triggered by cytoplasmic rather than external or periplasmic acidification and de novo protein synthesis was needed. Alkali sensitivity failed to appear at pH 5.5 plus DNA gyrase inhibitors and was markedly reduced by himA, himD, hns, ompC and nhaA lesions. A tonB deletion mutant showed alkali sensitivity at pH 7.0. Alkali sensitivity induction was not subject to catabolite repression nor was it appreciably affected by a relA lesion. Acid-induced cells were more sensitive to alkali damage to both DNA and β-galactosidase and to alkali inhibition of β-galactosidase induction. Alkali sensitization induced at pH 5.5 may involve NhaB loss.     

The Amyloid Precursor Protein Is Not Enriched in Caveolae-Like, Detergent-Insoluble Membrane Microdomains

Abstract: The amyloid precursor protein may be processed by several different pathways, one of which produces the amyloid β-peptide βA4 present in the amyloid plaques characteristic of Alzheimer's disease. A recent report suggested that axonal-amyloid precursor protein is present in a membrane fraction "with caveolae-like properties." In the present study we have isolated detergent-insoluble, caveolae-like membranes from both mouse cerebellum and the human neuroblastoma cell line SH-SY5Y. Detergent-insoluble membranes from mouse cerebellum retained nearly all of the glycosylphosphatidylinositol-anchored proteins—alkaline phosphatase, 5'-nucleotidase, and the F3 protein—while excluding the majority of the plasmalemmal marker protein alkaline phosphodiesterase I. Although the inositol trisphosphate receptor was highly enriched in this detergent-insoluble fraction, neither amyloid precursor protein nor clathrin immunoreactivity could be detected. Similar results were obtained with SH-SY5Y cells, where 5'-nucleotidase activity was enriched at least 30-fold in the detergent-insoluble membranes, but no amyloid precursor protein or clathrin immunoreactivity could be detected. Caveolin could not be detected in microsomal membranes from either mouse cerebellum or SH-SY5Y cells. These observations suggest that amyloid precursor protein is not normally present in detergent-insoluble, caveolae-like membrane microdomains.     

The effect of applied sulphur on the growth, grain yield and control of powdery mildew in spring wheat

During the years 1998 and 1999, two field experiments were conducted at the University of Wales, Aberystwyth, UK, to test the effects of soil‐ and foliar‐applied sulphur (S) in spring wheat. S was applied at 0, 20, 40, 60 kg ha^?1 in 1998 and at 60 kg ha^?1 in 1999, using CaSO₄ as a source for the soil application and micronised S (Thiovit, 80%), with and without an organosilicone adjuvant, as a source for the foliar application. Senescence was retarded and grain yield was increased in 1998, following application of foliar S in conjunction with the organosilicone adjuvant. Application of foliar S was associated with a reduction in the level of mildew (Erysiphe graminis) recorded on the upper leaves and ears of the canopy. In 1999, grain yield was unaffected by treatments. A low level of mildew in the crop, particularly on the ears, is thought to be the reason for the lack of response in spite of the fact that senescence was retarded with foliar S application. A combined application of foliar S and commercial fungicide (cyproconazole) to the crop appeared to be more effective at controlling mildew than either S or fungicide applied alone. The study shows that there may be a role for S in a low‐input/organic wheat production system, where there is a need to reduce artificial inputs.     

Role of endothelium-derived relaxing factor in active hyperemia of the canine diaphragm.

To assess the effect of endothelium-derived relaxing factor (EDRF) on diaphragmatic vascular resistance at rest and during contractions, we studied an in situ isolated diaphragm preparation in anesthetized and mechanically ventilated dogs. The arterial supply of the left diaphragm (phrenic artery) was catheterized and perfused with arterial blood at a fixed flow rate. Drugs were infused through a side port of the arterial catheter at 1/100th of the phrenic arterial flow. The inferior phrenic vein was catheterized to complete the isolation from the systemic circulation. Three sets of experiments were performed. In set 1 (n = 3), we infused endothelium-dependent (acetylcholine, ACh) and endothelium-independent (sodium nitroprusside, SNP) dilators at increasing concentrations. ACh and SNP infusion elicited a dose-dependent decline in phrenic vascular resistance (Rphr) at concentrations greater than 10(-8) M and 0.50 micrograms/ml, respectively. In set 2 (n = 15), we infused an inhibitor of EDRF synthesis and release, L-argininosuccinic acid (ArgSA), at increasing concentrations (10(-4), 3 x 10(-4), and 6 x 10(-4) M). ArgSA produced a dose-dependent increase in Rphr. Infusion of another EDRF inhibitor (NG-nitro-L-arginine, LNA, 6 x 10(-4) M) elicited increase in Rphr similar to that induced by ArgSA. In set 3 (n = 25), we infused ArgSA or LNA (6 x 10(-4) M) simultaneously with ACh and SNP and during sustained (2-Hz) contractions of the diaphragm. Both ArgSA and LNA completely reversed ACh vasodilation, whereas SNP vasodilation was reversed by 26 and 11%, respectively. ArgSA or LNA infusion during contractions reversed vasodilation by 48 and 52%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

A seven-gene operon essential for formate-dependent nitrite reduction to ammonia by enteric bacteria

The DNA sequence of the regulatory region and the structural gene, nrfA, for cytochrome C₅₅₂ of Escherichia coli K-12 have been reported. We have now established that nrfA is the first gene in a seven-gene operon, designated the nrf operon, at least five of which are essential for formate-dependent nitrite reduction to ammonia. This operon terminates just upstream of the previously sequenced gltP gene encoding a sodium-independent, glutamate and aspartate transporter. Expression of lac fused to nrfA, nrfE or nrfG is regulated by oxygen repression, FNR-dependent anaerobic induction, nitrite induction and nitrate repression during anaerobic growth, exactly as previously reported for the nrfA promoter, in contrast, expression of the gltP-lac fusion was FNR-independent. The open reading frame immediately downstream of nrfA encodes NrfB, a hydrophilic, penta-haem cytochrome c with an M_r of 20714. The structure of the N-terminal region is typical of a signal peptide for a periplasmic protein: cleavage at the putative signal peptide cleavage site, Ala-26, would result in a periplasmic cytochrome with a molecular mass of 18kDa. The NrfC polypeptide, M_r 24567, contains 16 cysteine residues arranged in four clusters typical of the CooF super-family of non-haem iron-sulphur proteins. The NrfD sequence predicts a 318-residue hydrophobic protein with a distribution of acidic and basic amino acids which suggests that NrfD is an integral transmembrane protein with loops in both the periplasm and the cytoplasm. Proteins most similar to NrfD inciude the PsrC subunit of polysulphide reductase from Wolinella, but, as seven of the 10 most similar proteins are NADH-ubiquinone oxidoreductases, we propose that NrfD participates in the transfer of electrons from the quinone pool into the terminal components of the Nrf pathway. NrfE, M_r 60851, is predicted to be another hydrophobic, integral membrane protein homologous to the Ccl1 protein of Rhodobacter capsulatus, which has been implicated in the assembly of periplasmic c-type cytochromes. The sequence of the 127 residue NrfF poiypeptide, M_r 14522, is strikingly similar to the Ccl2 protein of R. capsulatus, especially in the putative haem-binding motif, RCPQCQNQN. The translation stop codons of nrfE and nrfF overlap the start codons of nrfF and nrfG, respectively, suggesting that expression of nrfE, nrfF and nrfG may be translationally coupled. However sequence analysis suggests no apparent role for NrfG, although the sequence shows some similarities with the RecA protein from Synechococcus. The synthesis of two c-type cytochromes in wild-type bacteria, but not in an nrf deletion mutant, during anaerobic growth in the presence of nitrite was confirmed. Furthermore, we demonstrate over-expression of several Nrf polypeptides and GalE Nrf fusion proteins: in each case, the sizes of the products were consistent with the predicted sequence. Two alternative proposals for how the components of the Nrf pathway might be organized across the cytoplasmic membrane are presented.     

4-Fluoroproline derivative peptides: effect on PPII conformation and SH3 affinity.

Eukaryotic signal transduction involves the assembly of transient protein-protein complexes mediated by modular interaction domains. Specific Pro-rich sequences with the consensus core motif PxxP adopt the PPII helix conformation upon binding to SH3 domains. For short Pro-rich peptides, little or no ordered secondary structure is usually observed before binding interactions. The association of a Pro-rich peptide with the SH3 domain involves unfavorable binding entropy due to the loss of rotational freedom on forming the PPII helix. With the aim of stabilizing the PPII helix conformation in the Pro-rich HPK1 decapeptide PPPLPPKPKF (P2), a series of P2 analogues was prepared, in which specific Pro positions were alternatively occupied by 4(S)- or 4(R)-4-fluoro-L-proline. The interactions of these peptides with the SH3 domain of the HPK1-binding partner HS1 were quantitatively analyzed by the NILIA-CD approach. A CD thermal analysis of the P2 analogues was performed to assess their propensity to adopt the PPII helix conformation. Contrary to our expectations, the K(d) values of the analogues were lower than that of the parent peptide P2. These results clearly show that the induction of a stable PPII helix conformation in short Pro-rich peptides is not sufficient to increase their affinity toward the SH3 domain and that the effect of 4-fluoroproline strongly depends on the position of this residue in the sequence and the chirality of the substituent in the pyrrolidine ring.