Carbon accumulation and distribution in Pinus massoniana and Cunninghamia lanceolata mixed forest ecosystem in Daqingshan, Guangxi, China

Carbon accumulation and distribution were studied at three sampling plots in a 13-year-old mixed planatation of Pinus massoniana and Cunninghamia lanceolata in Daqingshan, Guangxi, China. The results showed that carbon content varied with tissues and tree species, but the total carbon content of Pinus massoniana was higher than that of Cunninghamia lanceolata. The average tissue carbon contents of Pinus massoniana were: wood (58.6%) > root (56.3%) > branch (51.2%) > bark (49.8%) > leaf (46.8%), while those of Cunninghamia lanceolata were: bark (52.2%) > leaf (51.8%) > wood (50.2%) > root (47.5%) > branch (46.7%). The carbon contents of the soil (at a depth of 60cm) ranged from 1.45% to 1.84% with an average of 1.70%. Carbon contents were higher in the surface soil (0–20cm) than in the deep layer (below 20cm). The average carbon contents were the highest for trees (51.1%), followed by litter (48.3%), shrubs (44.1%), and herbs (33.0%). The biomass of the trees in the three plots ranged from 85.35 t hm^-2 to 101.35 t hm^-2 with an average of 93.83 t hm^-2, in which 75.7%–82.6% was Pinus massoniana. The biomass of the understory was 2.10–3.95 t hm^-2 with an average of 2.72 t hm^-2, while the standing stock of ground litter was 5.49–7.91 t hm^-2 with an average of 6.75 t hm^-2. The carbon storage in the mixed plantation reached the maximum in the soil layer (69.02%), followed by vegetation (29.03%), and standing litter (1.82%). The carbon storage in the tree layer occupied 23.90% of the total ecosystem and 97.7% of the vegetation layer. Pinus massoniana accounted for 65.39% of the total carbon storage in the tree layer. Tissue carbon storage was directly related to the corresponding amount of biomass. Trunks had the highest carbon storage, accounting for 53.23% of the trees in Pinus massoniana and 55.57% in Cunninghamia lanceolata, respectively. Roots accounted for about 19.22% of the total tree carbon. The annual net productivity of the mixed plantation was 11.46 t hm^-2a^-1, and that of sequestered carbon was 5.96 t hm^-2a^-1, which was equivalent to fixing CO₂ of 21.88 t hm^-2a^-1. The plantation was found to be an important sink of atmospheric CO₂.     

MRI Features in a Canine Model of Ischemic Stroke: Correlation between Lesion Volume and Neurobehavioral Status during the Subacute Stage

The purpose of this study was to evaluate the diagnostic value of magnetic resonance imaging (MRI) and assess the correlation between the volume of the ischemic lesion and neurobehavioral status during the subacute stage of ischemic stroke. Ischemic stroke was induced in 6 healthy laboratory beagles through permanent occlusion of the middle cerebral artery (MCAO). T2-weighted and fluid-attenuated inversion recovery (FLAIR) imaging, diffusion-weighted imaging (DWI), measurement of the apparent diffusion coefficient (ADC) ratio, and neurobehavioral evaluation were performed 3 times serially by using a 1.5-T MR system: before and 3 and 10 d after MCAO. Ischemic lesions demonstrated T2 hyperintensity, FLAIR hyperintensity, and DWI hyperintensity. The ADC ratio was decreased initially but then was increased at 10 d after MCAO. Ischemic lesion volumes on T2-weighted and FLAIR imaging were not significantly different from those on DWI. The lesion volume and neurobehavioral score showed strong correlation. Our results suggest that conventional MRI may be a reliable diagnostic tool during the subacute stage of canine ischemic stroke.Abbreviations: ADC, apparent diffusion coefficient; DWI, diffusion-weighted imaging; FLAIR, fluid-attenuated inversion recovery; MCAO, middle cerebral artery occlusion; MRI, magnetic resonance imaging; PWI, perfusion-weighted imagingIn human medicine, stroke is a leading cause of adult mortality and neurologic disability worldwide.¹ Strokes previously were thought to be uncommon in small animals, but the true prevalence is unknown.⁴ These events are now recognized more frequently in dogs because of increased use of magnetic resonance imaging (MRI).^5,14,17Because the infusion of thrombolytic agents, such as urokinase or tissue plasminogen activator, within 3 to 6 h of the onset symptoms is effective in restoring blood flow and improving stroke outcome in humans,¹⁹ the detection of early ischemic changes is now thought to be necessary to improve patient outcome. Computed tomography and conventional MRI are not sufficiently sensitive to predict the presence and extent of ischemic damage during the acute stage after a stroke.^12,20 Therefore several MRI sequences, such as fluid-attenuated inversion recovery (FLAIR), diffusion-weighted imaging (DWI), perfusion-weighted imaging (PWI), and MR angiography, have been developed for early diagnosis and subsequent follow-up of ischemic stroke.³ High-field magnetic strengths (at least 1.5 T) are necessary to perform these sequences.In contrast to the situation in humans, ischemic stroke in many dogs is diagnosed during the subacute stage—24 h to 6 wk after the vascular insult—due to the time lag between the onset of clinical signs to referral and to the lack of standard diagnostic protocols for ischemic stroke in dogs. In most reports of strokes in dogs, the median interval between the onset of neurologic dysfunction and performance of an MRI was more than 2 d.^5,14,17 Whereas DWI has marked sensitivity to very early ischemic changes in the brain, T2-weighted and FLAIR images gradually become more hyperintense later (that is, during the first 24 h after the insult).³ Therefore, hyperintensity on T2-weighted and FLAIR images is believed to be representative of mature lesions.¹⁵ In light of these findings, we hypothesized that conventional MR sequences, such as T2-weighted and FLAIR imaging as well as DWI would be used for the diagnosis of the subacute stage of ischemic stroke in dogs.The purpose of this study was to evaluate the diagnostic value of MRI and assess the correlation between the volume of ischemic lesions and neurobehavioral status during the subacute stage of ischemic stroke in dogs. We therefore investigated the lesion volume of T2-weighted and FLAIR images compared with that on DWI images. Furthermore, we assessed the relationship between the apparent diffusion coefficient (ADC) of the ischemic lesions and the neurobehavioral status of the dogs.     

Adult Cardiac Progenitor Cell Aggregates Exhibit Survival Benefit Both In Vitro and In Vivo

Background

A major hurdle in the use of exogenous stems cells for therapeutic regeneration of injured myocardium remains the poor survival of implanted cells. To date, the delivery of stem cells into myocardium has largely focused on implantation of cell suspensions.

Methodology and Principal Findings

We hypothesize that delivering progenitor cells in an aggregate form would serve to mimic the endogenous state with proper cell-cell contact, and may aid the survival of implanted cells. Microwell methodologies allow for the culture of homogenous 3D cell aggregates, thereby allowing cell-cell contact. In this study, we find that the culture of cardiac progenitor cells in a 3D cell aggregate augments cell survival and protects against cellular toxins and stressors, including hydrogen peroxide and anoxia/reoxygenation induced cell death. Moreover, using a murine model of cardiac ischemia-reperfusion injury, we find that delivery of cardiac progenitor cells in the form of 3D aggregates improved in vivo survival of implanted cells.

Conclusion

Collectively, our data support the notion that growth in 3D cellular systems and maintenance of cell-cell contact improves exogenous cell survival following delivery into myocardium. These approaches may serve as a strategy to improve cardiovascular cell-based therapies.     

Characterisation and transferability of apple SSRs to two European pear F<Subscript>1</Subscript> populations

European pear (Pyrus communis L.) is among the important fruit species for which only few genetic studies have been carried out. Available evidence indicates that simple sequence repeats (SSR) are very useful as molecular markers because they are codominant, highly polymorphic, abundant and reproducible. The present paper reports more than 100 apple SSR markers in two populations of European pear; a total of 41 SSR markers were then positioned on a genetic linkage map of the cross Passe Crassane × Harrow Sweet and 31 in the map Abbè Fétel × Max Red Bartlett. Syntenic relationships between pear and apple maps have been considered for the chromosomes carrying two or more SSR markers. The alignment among the two maps supports the colinearity of the two genomes with respect both to identification and to orientation of the linkage groups.     

Molecular determinants of the cofactor specificity of ribitol dehydrogenase, a short-chain dehydrogenase/reductase

Ribitol dehydrogenase from Zymomonas mobilis (ZmRDH) catalyzes the conversion of ribitol to d-ribulose and concomitantly reduces NAD(P)(+) to NAD(P)H. A systematic approach involving an initial sequence alignment-based residue screening, followed by a homology model-based screening and site-directed mutagenesis of the screened residues, was used to study the molecular determinants of the cofactor specificity of ZmRDH. A homologous conserved amino acid, Ser156, in the substrate-binding pocket of the wild-type ZmRDH was identified as an important residue affecting the cofactor specificity of ZmRDH. Further insights into the function of the Ser156 residue were obtained by substituting it with other hydrophobic nonpolar or polar amino acids. Substituting Ser156 with the negatively charged amino acids (Asp and Glu) altered the cofactor specificity of ZmRDH toward NAD(+) (S156D, [k(cat)/K(m)(,NAD)]/[k(cat)/K(m)(,NADP)] = 10.9, where K(m)(,NAD) is the K(m) for NAD(+) and K(m)(,NADP) is the K(m) for NADP(+)). In contrast, the mutants containing positively charged amino acids (His, Lys, or Arg) at position 156 showed a higher efficiency with NADP(+) as the cofactor (S156H, [k(cat)/K(m)(,NAD)]/[k(cat)/K(m)(,NADP)] = 0.11). These data, in addition to those of molecular dynamics and isothermal titration calorimetry studies, suggest that the cofactor specificity of ZmRDH can be modulated by manipulating the amino acid residue at position 156.     

Inhibition of CLIC4 enhances autophagy and triggers mitochondrial and ER stress-induced apoptosis in human glioma U251 cells under starvation

CLIC4/mtCLIC, a chloride intracellular channel protein, localizes to mitochondria, endoplasmic reticulum (ER), nucleus and cytoplasm, and participates in the apoptotic response to stress. Apoptosis and autophagy, the main types of the programmed cell death, seem interconnected under certain stress conditions. However, the role of CLIC4 in autophagy regulation has yet to be determined. In this study, we demonstrate upregulation and nuclear translocation of the CLIC4 protein following starvation in U251 cells. CLIC4 siRNA transfection enhanced autophagy with increased LC3-II protein and puncta accumulation in U251 cells under starvation conditions. In that condition, the interaction of the 14-3-3 epsilon isoform with CLIC4 was abolished and resulted in Beclin 1 overactivation, which further activated autophagy. Moreover, inhibiting the expression of CLIC4 triggered both mitochondrial apoptosis involved in Bax/Bcl-2 and cytochrome c release under starvation and endoplasmic reticulum stress-induced apoptosis with CHOP and caspase-4 upregulation. These results demonstrate that CLIC4 nuclear translocation is an integral part of the cellular response to starvation. Inhibiting the expression of CLIC4 enhances autophagy and contributes to mitochondrial and ER stress-induced apoptosis under starvation.     

Ovarian cancer gene therapy using HPV-16 pseudovirion carrying the HSV-tk gene

Ovarian cancer is the leading cause of death from all gynecological cancers and conventional therapies such as surgery, chemotherapy, and radiotherapy usually fail to control advanced stages of the disease. Thus, there is an urgent need for alternative and innovative therapeutic options. We reason that cancer gene therapy using a vector capable of specifically delivering an enzyme-encoding gene to ovarian cancer cells will allow the cancer cell to metabolize a harmless prodrug into a potent cytotoxin, which will lead to therapeutic effects. In the current study, we explore the use of a human papillomavirus (HPV) pseudovirion to deliver a herpes simplex virus thymidine kinase (HSV-tk) gene to ovarian tumor cells. We found that the HPV-16 pseudovirion was able to preferentially infect murine and human ovarian tumor cells when administered intraperitoneally. Furthermore, intraperitoneal injection of HPV-16 pseudovirions carrying the HSV-tk gene followed by treatment with ganciclovir led to significant therapeutic anti-tumor effects in murine ovarian cancer-bearing mice. Our data suggest that HPV pseudovirion may serve as a potential delivery vehicle for ovarian cancer gene therapy.     

Novel potassium N-[(2S,3R,4R,5R)-2,3,4,5,6-pentahydroxylhex-1-yl]-L-amino acid dichloroplatinates(II) with high anti-tumor activity and low side reaction

To discover whether novel anti-tumor platinum agents are capable of selectively accumulating in tumor tissue, three novel potassium N-[(2S,3R,4R,5R)-2,3,4,5,6-pentahydroxylhex-1-yl]-L-amino acid dichloroplatinates(II) were prepared. At a dose of 1.67 μmol kg(-1) the in vivo anti-tumor potencies of two of the compounds were higher than that of oxaliplatin. The mortality analysis indicated that these compounds resulted in a 100% survival rate, whereas oxaliplatin lead to an 80% survival rate. The organ damage examination indicated that these compounds induced less damage than oxaliplatin. The platinum accumulation in the organs, blood and bone was significantly lower than that of oxaliplatin treated mice, while the platinum accumulation in the tumor tissue was significantly higher than that of the oxaliplatin treated mice.