Interspecific differences in the responses of root phosphatase activities and morphology to nitrogen and phosphorus fertilization in Bornean tropical rain forests.

Soil organic phosphorus (P) compounds can be the main P source for plants in P-limited tropical rainforests. Phosphorus occurs in diverse chemical forms, including monoester P, diester P, and phytate, which require enzymatic hydrolysis by phosphatase into inorganic P before assimilation by plants. The interactions between plant interspecific differences in organic P acquisition strategies via phosphatase activities with root morphological traits would lead to P resource partitioning, but they have not been rigorously evaluated. We measured the activities of three classes of phosphatases (phosphomonoesterase, PME; phosphodiesterase, PDE; and phytase, PhT), specific root length (SRL), root diameter, and root tissue density in mature tree species with different mycorrhizal associations (ectomycorrhizal [ECM] or arbuscular mycorrhizal [AM]) and different successional status (climax or pioneer species) in Sabah, Malaysia. We studied nitrogen (N)- and P-fertilized plots to evaluate the acquisition strategies for organic P under P-limited conditions 7 years after fertilization was initiated. P fertilization reduced the PME activity in all studied species and reduced PhT and PDE activities more in climax species than in the two pioneer species, irrespective of the mycorrhizal type. PDE activity increased in some climax species after N fertilization, suggesting that these species allocate excess N to the synthesis of PDE. Moreover, PME and PhT activities, but not PDE activity, correlated positively with SRL. We suggest that climax species tend to be more strongly dependent on recalcitrant organic P (i.e., phytate and/or diester P) than pioneer species, regardless of the mycorrhizal type. We also suggest that trees in which root PME or PhT activity is enhanced can increase their SRL to acquire P efficiently. Resource partitioning of soil organic P would occur among species through differences in their phosphatase activities, which plays potentially ecologically important role in reducing the competition among coexisting tree species in lowland tropical rainforests.

Correction: Factors affecting forest area change in Southeast Asia during 1980-2010.

[This corrects the article DOI: 10.1371/journal.pone.0197391.].

Factors affecting forest area change in Southeast Asia during 1980-2010.

While many tropical countries are experiencing rapid deforestation, some have experienced forest transition (FT) from net deforestation to net reforestation. Numerous studies have identified causative factors of FT, among which forest scarcity has been considered as a prerequisite for FT. In fact, in SE Asia, the Philippines, Thailand and Viet Nam, which experienced FT since 1990, exhibited a lower remaining forest area (30±8%) than the other five countries (68±6%, Cambodia, Indonesia, Laos, Malaysia, and Myanmar) where forest loss continues. In this study, we examined 1) the factors associated with forest scarcity, 2) the proximate and/or underlying factors that have driven forest area change, and 3) whether causative factors changed across FT phases (from deforestation to net forest gain) during 1980-2010 in the eight SE Asian countries. We used production of wood, food, and export-oriented food commodities as proximate causes and demographic, social, economic and environmental factors, as well as land-use efficiency, and wood and food trade as underlying causes that affect forest area change. Remaining forest area in 1990 was negatively correlated with population density and potential land area of lowland forests, while positively correlated with per capita wood production. This implies that countries rich in accessible and productive forests, and higher population pressures are the ones that have experienced forest scarcity, and eventually FT. Food production and agricultural input were negatively and positively correlated, respectively, with forest area change during 1980-2009. This indicates that more food production drives deforestation, but higher efficiency of agriculture is correlated with forest gain. We also found a U-shaped response of forest area change to social openness, suggesting that forest gain can be achieved in both open and closed countries, but deforestation might be accelerated in countries undergoing societal transition. These results indicate the importance of environmental, agricultural and social variables on forest area dynamics, and have important implications for predicting future tropical forest change.

Co-benefits of sustainable forest management in biodiversity conservation and carbon sequestration.

BACKGROUND: Sustainable forest management (SFM), which has been recently introduced to tropical natural production forests, is beneficial in maintaining timber resources, but information about the co-benefits for biodiversity conservation and carbon sequestration is currently lacking. METHODOLOGY/PRINCIPAL FINDINGS: We estimated the diversity of medium to large-bodied forest-dwelling vertebrates using a heat-sensor camera trapping system and the amount of above-ground, fine-roots, and soil organic carbon by a combination of ground surveys and aerial-imagery interpretations. This research was undertaken both in SFM applied as well as conventionally logged production forests in Sabah, Malaysian Borneo. Our carbon estimation revealed that the application of SFM resulted in a net gain of 54 Mg C ha(-1) on a landscape scale. Overall vertebrate diversity was greater in the SFM applied forest than in the conventionally logged forest. Specifically, several vertebrate species (6 out of recorded 36 species) showed higher frequency in the SFM applied forest than in the conventionally logged forest. CONCLUSIONS/SIGNIFICANCE: The application of SFM to degraded natural production forests could result in greater diversity and abundance of vertebrate species as well as increasing carbon storage in the tropical rain forest ecosystems.

Increased mobilization of c-kit+ Sca-1+ Lin- (KSL) cells and colony-forming units in spleen (CFU-S) following de novo formation of a stem cell niche depends on dynamic, but not stable, membranous ossification.

Stem cells are thought to inhabit in a unique microenvironment, known as "niche," in which they undergo asymmetric cell divisions that results in reproducing both stem cells and progenies to maintain various tissues throughout life. The cells of osteoblastic lineage have been identified as a key participant in regulating the number of hematopoietic stem cells (HSCs). HSCs receive their regulatory messages from the microenvironment in the bone marrow. This would account for a reason why the localization of hematopoiesis is usually restricted in the bone marrow. To clarify the above possibility we employed a cell implantation-based strategy with a unique osteoblast cell line (KUSA-A1) derived from a C3H/He mouse. The implantation of KUSA-A 1 cells resulted in the generation of ectopic bones in the subcutaneous tissues of the athymic BALB/c nu/nu mice. Subsequently the mice obtained a greater amount of the bone marrow than normal mice, and they showed an increased number of HSCs. These results indicate that the newly generated osteoblasts-derived ectopic bones are responsible for the increase in the number of the HSC population. Furthermore, the increased number of HSCs directly correlates with both the magnitude of dynamic osteogenic process and the size of the newly generated bone or "niche."

Severe hyperparathyroidism with bone abnormalities and metastatic calcification in rats with adenine-induced uraemia.

BACKGROUND: Marked parathyroid hyperplasia with bone diseases and vascular calcification are unsolved issues in dialysis patients. In this study, we made azotemic model rats by adenine feeding and analyzed the development and progression of the abnormalities. METHODS: Renal failure was induced in 8-week-old male Wistar rats by feeding 0.75% adenine-containing diet for 6 weeks. Serum parameters, parathyroid hyperplasia, bone changes and metastatic calcification were examined at 2, 4 and 6 weeks. RESULTS: Progressive increase of serum creatinine and inorganic phosphate, and decreased levels of serum calcium and 1,25(OH)2D3 were confirmed. Markedly enlarged parathyroid glands and extremely high PTH levels were observed in all adenine-fed rats compared with the control (PTH: 199.3+/-58.0 vs 10.5+/-3.0 pmol/l, P<0.01, respectively, at 6 weeks). In cortical bone of the femur, the morphometric parameters showed increased bone resorption with increased fibrosis, whereas in the trabecular bone, bone resorption decreased and bone volume increased with a larger amount of osteoid compared with the control. Metastatic calcification in aorta, coronary artery and other soft tissues were also found in adenine-fed rats. CONCLUSIONS: Uraemic rats made by adenine diet developed severe abnormalities of calcium metabolism in a relatively short period and therefore they may serve as a useful model for the analysis of parathyroid hyperplasia and vascular calcification in chronic renal failure.

Receptor microscopic autoradiography for the study of percutaneous absorption, in vivo skin penetration, and cellular-intercellular deposition.

INTRODUCTION: Microscopic autoradiography with cellular resolution and preservation of in vivo conditions is potentially the method of choice to gain detailed information about sites of deposition and retention in the epidermis and of penetration to the dermis after topical application of drugs. We tested this using (3)H-Maxacalcitol. METHODS: Dorsal skin of adult rats was treated in vivo with ointment containing 1 or 40 microg/kg body weight of the vitamin D analogue (3)H-Maxacalcitol for periods of 0.5, 2, 8, 24, 48, or 168 h. Samples of skin exposed to the ointment and control samples remote from the treatment site were excised and freeze-mounted, and 4-microm frozen sections were exposed to nuclear emulsion. RESULTS: Two penetration routes to the dermis could be distinguished: one via epidermal cell layers and the other via hair follicles. Highest uptake and retention of radiolabeled steroid was observed in stratum corneum and in intercellular spaces of stratum granulosum. By contrast, cell boundaries and intercellular spaces in the stratum spinosum and basale contained low levels of radioactivity. Keratinocytes in these layers showed high concentration in the cytoplasm at early time intervals, when surrounding radioactivity levels were high, but high nuclear and low or no cytoplasmic concentration at late time intervals, when surrounding radioactivity levels were low. DISCUSSION: The autoradiographic method provides detailed information on time- and dose-related distribution of radiolabeled compound at the cellular level that is not obtainable with common radioassays and biochemical procedures. A sustained concentration and retention of radiolabeled steroid in the stratum corneum and intercellular space of the stratum granulosum indicate a selective deposition in components of secreted-membrane-coating granules and suggest a temporary barrier and depot for slow release. The differential cytoplasmic-nuclear distribution in the stratum Malpighi suggests functional correlation to a toxic-hormetic reversal of action on cell proliferation, from high-dose inhibitory effects associated with high extranuclear concentration as utilized in the treatment of psoriasis, to low-dose stimulatory effects associated with high nuclear and low cytoplasmic concentration as applicable in wound healing.

Nicorandil and leukocyte activation.

Nicorandil, a hybrid compound of an ATP-sensitive potassium (KATP ) channel opener and a nitric oxide donor, has been reported to preserve microvascular integrity in patients with reperfused myocardial infarction. The aim of the current study was to test the hypothesis that nicorandil suppresses activation of polymorphonuclear leukocytes (PMNLs), resulting in reduction of PMNL migration into tissue upon ischemia/reperfusion. Nicorandil, along with the mitochondrial KATP channel opener diazoxide and the nitric oxide donors nitroglycerin and isosorbide dinitrate, suppressed pseudopod projection in human PMNLs treated with 10(-9)-formyl-methionyl-leucyl-phenylalanine (FMLP) and subjected to shear stress (5 dyn/cm(2)) with a cone-and-plate shear device. Suppression by nicorandil and diazoxide was reversed by KATP channel blockers, 5 hydroxydecanoate and glibenclamide. FMLP-induced increase of [Ca2+] in PMNLs was suppressed by nicorandil and diazoxide, and 5 hydroxy-decanoate and glibenclamide reversed this suppression. Results of reverse transcription polymerase chain reaction with rat PMNL mRNA indicated the presence of mRNAs of Kir6.2 and Kir6.1 but not mRNAs of sulfonylurea receptor 1 or 2. Isosorbide dinitrate, diazoxide, and nicorandil reduced leukocyte migration and microvascular obstruction in reperfused ischemic tissue of rat mesenteric microcirculation. In conclusion, nicorandil attenuates ischemia/reperfusion-induced PMNL activation via donation of nitric oxide and K channel-related cascade.