Vegetation-edaphic correlation and importance value index in himalayan 'ecotone' temperate conifer forest using the multivariate technique

Himalayan 'Ecotone' temperate conifer forest is the cradle of life for human survival and wildlife existence. In spite of the importance of these areas, they have not been studied in depth. This study aimed to quantify the floristic structure, important value index (IVI), topographic and edaphic variables between 2019 and 2020 utilizing circular quadrant method (10 m x 10 m). The upper-storey layer consisted of 17 tree species belongs to 12 families and 9 orders. Middle-storey shrubs comprised of 23 species representing 14 families and 12 orders. A total of 43 species of herbs, grasses, and ferns were identified from the ground-storey layer, representing 25 families and 21 orders. Upper-storey vegetation structure was dominated by Pinus roxburghii (22.45 %) and middle-storey by Dodonaea viscosa (7.69 %). However, the ground layer vegetation was diverse in species composition (43 species) and distribution. The floral vegetation structure was encompassing of three floral communities which were diverse in IVI, such as, in Piro-Aial (Group 2), Pinus roxburghii (54.46 x 15.94) had the highest IVI value, followed by Pinus wallichiana (45.21 x 14.85) in Piwa-Quin (Group 3) and Ailanthus altissima (22.84 x 19.25) in Aial-Qugal (Group 1). However, the IVI values for Aesculus indica, Celtis australis, and Quercus incana in Aial-Qugal (Group 1) were not determined due to low detection rate. Nevertheless, eleven of these species showed 0 IVI values in Piro-Aial (Group 2) and Piwa-Quin (Group 3). CCA ordination biplot illustrated the significant differences among floral communities and its distribution, which impacted by temperature, rainfall, soil pH, altitude, and topographic features. Ward's agglomerative clustering finding reflected 'Ecotone' temperate conifer forest is rich and diverse floristic structure.

Suppression of the mTOR-raptor signaling pathway by the inhibitor of heat shock protein 90 geldanamycin

Heat shock protein 90 (Hsp90) was co-immunoprecipitated with raptor, the binding partner of the mammalian target of rapamycin (mTOR) from HEK293 cells. Hsp90 was detected in the anti-raptor antibody immunoprecipitates prepared from the cell extract by immunoblot analysis using the anti-Hsp90 antibody, and the association of these two proteins was confirmed by immunoprecipitation from the cells co-expressing Hsp90 and raptor as epitope-tagged molecules. Geldanamycin, a potent inhibitor of Hsp90, disrupted the in vivo binding of Hsp90 to raptor without affecting the association of raptor and mTOR, and suppressed the phosphorylation by mTOR of the downstream translational regulators p70 S6 kinase (S6K) and eukaryotic initiation factor 4E-binding protein 1 (4E-BP1). The protein kinase activity of S6K as well as the phosphorylation of the substrate, 40S ribosomal protein S6, were lowered in the geldanamycin-treated cells. These results indicate that Hsp90 is involved in the regulation of protein translation by facilitating the phosphorylation reaction of 4E-BP1 and S6K catalyzed by the mTOR/raptor complex through the association with raptor, and that the mTOR signaling pathway is a novel target of geldanamycin.

Different roles for the TOS and RAIP motifs of the translational regulator protein 4E-BP1 in the association with raptor and phosphorylation by mTOR in the regulation of cell size

The translational regulator protein 4E-BP1, that binds to eukaryotic initiation factor-4E (eIF4E) to prevent the formation of the active translation complex, dissociates from eIF4E by phosphorylation through the mammalian target of rapamycin (mTOR) in the cells stimulated by amino acids. 4E-BP1 has been shown to associate with the scaffold protein raptor through its TOS and RAIP motifs to be recognized by mTOR. We revealed that the TOS motif mutant was phosphorylated by mTOR only at the priming sites of Thr37/46 but the RAIP motif mutant was phosphorylated not only at the priming sites but also at the subsequent site of Thr70 in vitro and in response to amino acid treatment in HEK293 cells. Analysis using the phosphorylation site mutants indicated that phosphorylation of the priming and subsequent sites of 4E-BP1 was required for dissociation from raptor as well as for the release of eIF4E. The expression of the 4E-BP1 mutants replacing the TOS motif and phosphorylation sites, that are poor substrates for mTOR and have no or little dissociation ability from raptor and eIF4E, respectively, significantly reduced the size of K562 cells. These results indicate that the the TOS motif has an essential function whereas the RAIP motif has an accessory role in the association with raptor and mTOR-mediated phosphorylation of 4E-BP1 to dissociate it from raptor and release eIF4E in response to amino acid stimulation leading to the control of cell size.

Dissociation of raptor from mTOR is a mechanism of rapamycin-induced inhibition of mTOR function

The mammalian target of rapamycin (mTOR) is a Ser/Thr protein kinase that plays a crucial role in a nutrient-sensitive signalling pathway that regulates cell growth. TOR signalling is potently inhibited by rapamycin, through the direct binding of a FK506-binding protein 12 (FKBP12)/rapamycin complex to the TOR FRB domain, a segment amino terminal to the kinase catalytic domain. The molecular basis for the inhibitory action of FKBP12/rapamycin remains uncertain. Raptor (regulatory associated protein of mTOR) is a recently identified mTOR binding partner that is essential for mTOR signalling in vivo, and whose binding to mTOR is critical for mTOR-catalysed substrate phosphorylation in vitro. Here we investigated the stability of endogenous mTOR/raptor complex in response to rapamycin in vivo, and to the direct addition of a FKBP12/rapamycin complex in vitro. Rapamycin diminished the recovery of endogenous raptor with endogenous or recombinant mTOR in vivo; this inhibition required the ability of mTOR to bind the FKBP12/rapamycin complex, but was independent of mTOR kinase activity. Rapamycin, in the presence of FKBP12, inhibited the association of raptor with mTOR directly in vitro, and concomitantly reduced the mTOR-catalysed phosphorylation of raptor-dependent, but not raptor-independent substrates; mTOR autophosphorylation was unaltered. These observations indicate that rapamycin inhibits mTOR function, at least in part, by inhibiting the interaction of raptor with mTOR; this action uncouples mTOR from its substrates, and inhibits mTOR signalling without altering mTOR's intrinsic catalytic activity.

The mammalian target of rapamycin (mTOR) partner, raptor, binds the mTOR substrates p70 S6 kinase and 4E-BP1 through their TOR signaling (TOS) motif

The mammalian target of rapamycin (mTOR) controls multiple cellular functions in response to amino acids and growth factors, in part by regulating the phosphorylation of p70 S6 kinase (p70S6k) and eukaryotic initiation factor 4E-binding protein 1 (4E-BP1). Raptor (regulatory associated protein of mTOR) is a recently identified mTOR binding partner that also binds p70S6k and 4E-BP1 and is essential for TOR signaling in vivo. Herein we demonstrate that raptor binds to p70S6k and 4E-BP1 through their respective TOS (conserved TOR signaling) motifs to be required for amino acid- and mTOR-dependent regulation of these mTOR substrates in vivo. A point mutation of the TOS motif also eliminates all in vitro mTOR-catalyzed 4E-BP1 phosphorylation and abolishes the raptor-dependent component of mTOR-catalyzed p70S6k phosphorylation in vitro. Raptor appears to serve as an mTOR scaffold protein, the binding of which to the TOS motif of mTOR substrates is necessary for effective mTOR-catalyzed phosphorylation in vivo and perhaps for conferring their sensitivity to rapamycin and amino acid sufficiency.

Inhibition of amino acid-mTOR signaling by a leucine derivative induces G1 arrest in Jurkat cells

We have previously demonstrated that N-acetylleucine amide, a derivative of L-leucine, inhibits leucine-induced p70(S6k) activation in a rat hepatoma cell line. In the present study, we investigated whether N-acetylleucine amide is capable of inhibiting amino acid-mTOR signaling. N-Acetylleucine amide caused cell cycle arrest at G1 stage in Jurkat cells, a human leukemia T cell line, concomitant with the inhibition of serum-induced p70(S6k) activation and p27 degradation. Treatment of Jurkat cells with this compound also exhibited dephosphorylation of retinoblastoma protein. These effects are similar to the inhibitory effects of rapamycin on amino acid-mTOR signaling pathway and suggest that N-acetylleucine amide acts as a rapamycin-like reagent to inhibit cell cycle progression in Jurkat cells.

Raptor, a binding partner of target of rapamycin (TOR), mediates TOR action

mTOR controls cell growth, in part by regulating p70 S6 kinase alpha (p70alpha) and eukaryotic initiation factor 4E binding protein 1 (4EBP1). Raptor is a 150 kDa mTOR binding protein that also binds 4EBP1 and p70alpha. The binding of raptor to mTOR is necessary for the mTOR-catalyzed phosphorylation of 4EBP1 in vitro, and it strongly enhances the mTOR kinase activity toward p70alpha. Rapamycin or amino acid withdrawal increases, whereas insulin strongly inhibits, the recovery of 4EBP1 and raptor on 7-methyl-GTP Sepharose. Partial inhibition of raptor expression by RNA interference (RNAi) reduces mTOR-catalyzed 4EBP1 phosphorylation in vitro. RNAi of C. elegans raptor yields an array of phenotypes that closely resemble those produced by inactivation of Ce-TOR. Thus, raptor is an essential scaffold for the mTOR-catalyzed phosphorylation of 4EBP1 and mediates TOR action in vivo.

Respiratory symptoms, lung function, and nasal cellularity in Indonesian wood workers: a dose-response analysis

OBJECTIVES

It was hypothesised that inflammation plays a dominant part in the respiratory effects of exposure to wood dust. The purpose of this study was to relate the nasal inflammatory responses of workers exposed to meranti wood dust to (a) levels of exposure, (b) respiratory symptoms and (c) respiratory function.

METHODS

A cross sectional study was carried out in 1997 in a woodworking plant that used mainly meranti, among 982 workers exposed to different concentrations of wood dust. Personal sampling (n=243) of inhalable dust measurements indicated mean exposure in specific jobs, and enabled classification of 930 workers in three exposure classes (<2, 2-5, and >5 mg/m(3)) based on job title. Questionnaires were used to screen respiratory symptoms in the entire population. Lung function was measured with two different techniques, conventional flow-volume curves and the forced oscillation technique. Nasal lavage was done to assess inflammation in the upper respiratory tract.

RESULTS

A negative trend between years of employment and most flow-volume variables was found in men, but not in women workers. Current exposure, however, was not related to spirometric outcomes, respiratory symptoms, or nasal cellularity. Some impedance variables were related to current exposure but also with better function at higher exposure.

CONCLUSIONS

Exposure to meranti wood dust did not cause an inflammation in the upper respiratory tract nor an increase of respiratory symptoms or decrease of lung function. These data do not corroborate the hypothesis that inflammation plays a part in airway obstruction induced by wood dust.

Carboxyl-terminal region conserved among phosphoinositide-kinase-related kinases is indispensable for mTOR function in vivo and in vitro

BACKGROUND

The mammalian target of rapamycin (mTOR) belongs to the family of phosphoinositide (PI)-kinase-related kinases that includes the ataxia-telangiectasia gene product (ATM). mTOR plays a critical role in controlling translational effectors such as p70 S6 kinase alpha (p70 alpha) and eukaryotic initiation factor 4E binding protein 1 (4EBP1).

RESULTS

We show that the C-terminal region of mTOR, which is highly conserved among the PI-kinase-related kinases, plays a critical role in the mTOR protein kinase activity. Deletion of the C-terminal residues did not adversely affect the expression of mTOR, but caused a nearly complete loss of the mTOR protein kinase activity toward both 4EBP1 and p70 alpha in vitro. These deletions also abolished the ability of a rapamycin-resistant mTOR mutant to rescue the activity of p70 alpha from inhibition induced by rapamycin in vivo. Furthermore, replacement of Trp2545, a conserved residue in the C-terminal region throughout the PI-kinase-related kinase family, abolished the function of the mTOR kinase, both in vivo and in vitro. However, substitution of 32 C-terminal residues of mTOR with those of ATM did not restore the mTOR function.

CONCLUSIONS

These findings define an indispensable role for the noncatalytic C-terminal region of mTOR and indicate that, although this highly conserved region may be important throughout the PI-kinase-related kinase family, it is not functionally interchangeable within the family.

Structural requirement of leucine for activation of p70 S6 kinase

The addition of leucine induced activation of p70S6k in amino acid-depleted H4IIE cells. Whereas the activation of p70S6k by leucine was transient, the complete amino acid stimulated p70S6k more persistently. The effect of leucine on p70S6k was sensitive to rapamycin, but less sensitive to wortmannin. Using various amino acids and derivatives of leucine, we found that the chirality, the structure of the four branched hydrocarbons, and the primary amine are required for the ability of leucine to stimulate p70S6k, indicating that the structural requirement of leucine to induce p70S6k activation is very strict and precise. In addition, some leucine derivatives exhibited the ability to stimulate p70S6k and the other derivatives acted as inhibitors against the leucine-induced activation of p70S6k.

Impact of neonatal vitamin A supplementation on infant morbidity and mortality

OBJECTIVE

To determine whether vitamin A supplementation at birth could reduce infant morbidity and mortality.

STUDY DESIGN

We conducted a placebo-controlled trial among 2067 Indonesian neonates who received either 52 micromol (50,000 IU) orally administered vitamin A or placebo on the first day of life. Infants were followed up at 1 year to determine the impact of this intervention on infant mortality. A subgroup (n = 470) was also examined at 4 and 6 months of age to examine the impact on morbidity.

RESULTS

Vital status was confirmed in 89% of infants in both groups at 1 year. There were 19 deaths in the control group and 7 in the vitamin A group (relative risk = 0.36; 95% confidence interval = 0.16, 0.87). The impact was stronger among boys, infants of normal compared with low birth weight, and those of greater ponderal index. Among infants examined at 4 months of age, the 1-week period prevalence of common morbidities was similar for vitamin A and control infants. However, during this same 4-month period, 73% and 51% more control infants were brought for medical treatment for cough (p = 0.008) and fever (p = 0.063), respectively.

CONCLUSIONS

Neonatal vitamin A supplementation may reduce the infant mortality rate and the prevalence of severe respiratory infection among young infants.

Safety of one 52-mumol (50,000 IU) oral dose of vitamin A administered to neonates

A placebo-controlled trial was carried out among 2067 Indonesian neonates to assess the safety of administering one oral 52-mumol (50,000 IU) dose of vitamin A. Infants were assessed for potential acute side-effects before and throughout 48 hours after the dose. The first 965 infants were examined by cranial ultrasound before and at 24 hours after dosing to rule out intracranial haemorrhage and determine the resistive index (RI) of the anterior cerebral artery using duplex Doppler. Groups were comparable at the baseline. A bulging fontanelle occurred in the control and vitamin A groups, respectively, among 2.7% and 4.6% of the infants at 24 hours, and 2.4% and 4.5% of the infants at 48 hours. The groups did not differ in any other sign or symptom assessed. No infant developed intracranial haemorrhage. Mean RI values were normal and not different between groups at baseline or at 24 hours. Mean RI fell during the 24 hours, as normally occurs; the mean decrease was nearly identical in the two groups. A bulging fontanelle was not associated with increased rates of any sign or symptom or with an increase in RI. The 52-mumol dose of oral vitamin A may cause a small increase in intracranial volume in a small proportion of infants, but no increase in intracranial pressure. Acute side-effects following this intervention were rare and mild.