Aboveground biomass dynamics of subalpine old-growth forest in the upper reach of the Minjiang River

Biomass estimation of old-growth forests in the upper Minjiang River (UMR) is important in quantifying carbon (C) sequestration and C sink size because majority of the natural forests in UMR are mature or over-mature. Based on the forest resource data from 27 fixed sampling plots that have been surveyed consecutively, the dynamics of the aboveground biomass density (AGBD) were characterized by the allometric relationships, and the space-time variations of the C sink size in the sub-alpine old-growth forests of UMR were explored. Our results showed that 1) the net increase in AGBD was (27.311 ± 15.580) Mg·hm^?2 and the mean annual growth rate and mean annual death rate were (1.930 ± 1.091) and (2.271 ± 1.424) Mg·hm^?2·a^?1 during 1988–2002, respectively. 2) The aboveground biomass (AGB) largely depended on the growth and death rates of the trees with different diameters at the breast height (DBH) classes and the recruitment rate from one DBH class to another as well. The largest increment component of AGB came from the DBH class of 20 to 40 cm, whereas the minimum increment component of AGB was above 80 cm in DBH. The net negative increment of AGB occurred at DBH classes of 40–60 and 60–80 cm. 3) There were space-time variations of AGB in the alpine old-growth forests, indicated by AGB changing over time in the same sampling plot and varying among the locations or plots during the same sampling period. These variations were not only reflected in numerical value but also in positive or negative biomass increment.     

Warburg-like effect is a hallmark of complex I assembly defects

Due to its pivotal role in NADH oxidation and ATP synthesis, mitochondrial complex I (CI) emerged as a crucial regulator of cellular metabolism. A functional CI relies on the sequential assembly of nuclear- and mtDNA-encoded subunits; however, whether CI assembly status is involved in the metabolic adaptations in CI deficiency still remains largely unknown. Here, we investigated the relationship between CI functions, its structure and the cellular metabolism in 29 patient fibroblasts representative of most CI mitochondrial diseases. Our results show that, contrary to the generally accepted view, a complex I deficiency does not necessarily lead to a glycolytic switch, i.e. the so-called Warburg effect, but that this particular metabolic adaptation is a feature of CI assembly defect. By contrast, a CI functional defect without disassembly induces a higher catabolism to sustain the oxidative metabolism. Mechanistically, we demonstrate that reactive oxygen species overproduction by CI assembly intermediates and subsequent AMPK-dependent Pyruvate Dehydrogenase inactivation are key players of this metabolic reprogramming. Thus, this study provides a two-way-model of metabolic responses to CI deficiencies that are central not only in defining therapeutic strategies for mitochondrial diseases, but also in all pathophysiological conditions involving a CI deficiency.     

Osteogenic effects of flavonoid aglycones from an osteoprotective fraction of Drynaria fortunei—An in vitro efficacy study

Drynaria fortunei (Kunze) J. Sm. is a traditional Chinese herb used for the treatment of osteoporosis and other bone metabolic disorders. Previous studies demonstrated that “small polar active fraction in Drynaria fortunei (SDF)”exerted osteoprotective effects in ovariectomized (OVX) mice. This study aims to investigate the constituents in SDF and systemically evaluate their osteogenic effects in vitro. Five flavonoid aglycones, naringenin, kurarinone, kushennol F, xanthogalenol, and sophoraflavanone G were identified in SDF. All the compounds did not show effects on proliferation of osteoblastic UMR 106 cells at the concentrations of 0.1-1000 nM, but significantly increased the ALP activity of the cells at most of the concentrations from 10 nm to 1000 nM. Xanthogalenol at the concentration of 100 nM significantly increased concentration of acid-solubilized calcium. ICI 182,780, antagonist of estrogen receptor (ER), diminished the effect of kushennol F on ALP activity and the effect of xanthogalenol on acid-solubilized calcium. In conclusion, flavonoid aglycones in SDF could promote differentiation and mineralization of osteoblastic UMR 106 cells in vitro, which was explained by activation of ER signaling pathway. This study provides scientific evidences for the conduction of in vivo experiments to confirm potential effects of flavonoid aglycones on preventing OVX-induced osteoporosis.     

Genetic contribution between APE1 variants in polycystic ovarian syndrome

IntroductionPolycystic Ovarian Syndrome (PCOS) has been identified as a gynecological, hormonal, and metabolic condition in women of reproductive age. Genetic studies can contribute to understand the pathogenesis of PCOS; which can be beneficial in early diagnosis and long-term management of the disease. Apurinic/apyrimidinic endonuclease 1 (APE1) has been related in the literature to polycystic ovarian syndrome.AimThe purpose of this study was to investigate the effects of ?656 T > G and 1349 T > G single nucleotide polymorphisms (SNPs) in the APE1 gene in Saudi women with PCOS.MethodsThis study includes 100 PCOS women and 100 healthy controls were genotyped for ?656 T > G and 1349 T > G SNPs using PCR-RFLP method. Serum sample was used for FBG and lipid profile tests. The obtained biochemical and genotypes data were entered into Excel and utilized for statistical analysis.ResultsClinical data presented in Table 1 was used to calculate the t-tests between PCOS and control subjects and results indicate age, weight, BMI, TG, LDLC and PCOS family history was associated (p < 0.0001). Genotype and allele frequencies showed the negative association in ?656 T > G SNP (GG vs TT: OR-1.15 (0.61–2.17); p = 0.65 and GG + TG vs TT: OR-1.17 (0.67–2.04); p = 0.57) and positive association in 1349 T > G SNP (GG vs TT: OR-3.52 (1.48–8.36); p = 0.003 and GG + TG vs TT: OR-2.84 (1.27–6.31); p = 0.008) in APE1 gene. Anova analysis was not associated with any one of the involved parameters (p > 0.05).ConclusionThis study found that the 1349 T > G SNP was related with PCOS in Saudi women. However, the ?656SNP had no favorable effect on the APE1 gene.     

The transmembrane domain of the SNARE protein VAMP2 is highly sensitive to its lipid environment

Neurotransmitter and hormone exocytosis depends on SNARE protein transmembrane domains and membrane lipids but their interplay is poorly understood. We investigated the interaction of the structure of VAMP2, a vesicular transmembrane SNARE protein, and membrane lipid composition by infrared spectroscopy using either the wild-type transmembrane domain (TMD), VAMP2_TM22, or a peptide mutated at the central residues G₁₀₀/C₁₀₃ (VAMP2_TM22VV) previously identified by us as being critical for exocytosis. Our data show that the structure of VAMP2_TM22, in terms of α-helices and β-sheets is strongly influenced by peptide/lipid ratios, by lipid species including cholesterol and by membrane surface charges. Differences observed in acyl chain alignments further underscore the role of the two central small amino acid residues G₁₀₀/C₁₀₃ within the transmembrane domain during lipid rearrangements in membrane fusion.     

Minimal nanodisc without exogenous lipids for stabilizing membrane proteins in detergent-free buffer

Membrane protein stabilization after detergent solubilization presents drawbacks for structural and biophysical studies, in particular that of a reduced stability in detergent micelles. Therefore, alternative methods are required for efficient stabilization. Lipid nanodisc made with the membrane scaffold protein MSP is a valuable system but requires a fine optimization of the lipid to protein ratio. We present here the use of the scaffold protein MSP without added lipids as a minimal system to stabilize membrane proteins. We show that this method is applicable to α-helical and β-strands transmembrane proteins. This method allowed cryo-electron microscopy structural study of the bacterial transporter MexB. A protein quantification indicates that MexB is stabilized by two MSP proteins. This simplified and efficient method proposes a new advance in harnessing the MSP potential to stabilize membrane proteins.     

The Glycine Residues G551 and G1349 within the ATP-Binding Cassette Signature Motifs Play Critical Roles in the Activation and Inhibition of Cystic Fibrosis Transmembrane Conductance Regulator Channels by Phloxine B

The cystic fibrosis transmembrane conductance regulator (CFTR) protein contains a canonical ATP-binding cassette (ABC) signature motif, LSGGQ, in nucleotide binding domain 1 (NBD1) and a degenerate LSHGH in NBD2. Here, we studied the contribution of the conserved residues G551 and G1349 to the pharmacological modulation of CFTR chloride channels by phloxine B using iodide efflux and whole-cell patch clamp experiments performed on the following green fluorescent protein (GFP)-tagged CFTR: wild-type, delF508, G551D, G1349D, and G551D/G1349D double mutant. We found that phloxine B stimulates and inhibits channel activity of wild-type CFTR (K_s = 3.2 ± 1.6 μM, K_i = 38 ± 1.4 μM) and delF508 CFTR (K_s = 3 ± 1.8 μM, K_i = 33 ± 1 μM). However, CFTR channels with the LSGDQ mutated motif (mutation G551D) are activated (K_s = 2 ± 1.13 μM) but not inhibited by phloxine B. Conversely, CFTR channels with the LSHDH mutated motif (mutation G1349D) are inhibited (K_i = 40 ± 1.01 μM) but not activated by phloxine B. Finally, the double mutant G551D/G1349D CFTR failed to respond not only to phloxine B stimulation but also to phloxine B inhibition, confirming the importance of both amino acid locations. Similar results were obtained with genistein, and kinetic parameters were determined to compare the pharmacological effects of both agents. These data show that G551 and G1349 control the inhibition and activation of CFTR by these agents, suggesting functional nonequivalence of the signature motifs of NBD in the ABC transporter CFTR.     

中药固真方对成骨样细胞UMR106增殖分化的影响

 中药固真方具有补肾益精、延缓衰老的作用 .为了进一步探讨其作用机理 ,研究观察了固真方对成骨样细胞 UMR1 0 6DNA合成、原癌基因 c- fos,c- ki- ras m RNA表达以及骨钙素 (osteocal-cin)基因 m RNA表达的影响 .结果表明 :固真方可明显促进 DNA合成 ,且在 1 0 -5稀释度时达高峰 ;增殖相关的原癌基因 (c- fos,c- ki- ras) m RNA表达增强 ;成熟成骨细胞特征性标志蛋白——骨钙素基因 m RNA表达增强 .结果提示 :中药固真方可能通过影响一些与增殖相关的原癌基因及骨钙素基因表达而促成骨样细胞 UMR1 0 6的增殖和分化成熟     

Echoes from the past: New insights into the early hominin cochlea from a phylo-morphometric approach

We investigate cochlear variation, an indirect evidence of auditory capacities among early hominins and extant catarrhine species, in order to assess (i) the phylogenetic signal of relative external cochlear length (RECL) and oval window area (OWA), (ii) the evolutionary model with the highest probability of explaining our observed data, (iii) some hominin ancestral nodes for RECL and OWA. RECL has a high phylogenetic signal under a Brownian motion model, and is closely correlated with body mass. Our model-based method has the advantage over parsimony-based methods of incorporating branch lengths in a phylo-morphospace, and this shows RECL shifted towards significantly higher values at the Homo erectus-Homo sapiens node. We also observe that the StW 53 and KB 6067 fossil specimens from Sterkfontein and Kromdraai likely represent one or two distinct, smaller-bodied and less derived hominin form(s) compared to Paranthropus specimens represented at Swartkrans.