Associations between forest fragmentation patterns and genetic structure in Pfrimer’s Parakeet (Pyrrhura pfrimeri), an endangered endemic to central Brazil’s dry forests

When habitat becomes fragmented, populations of species may become increasingly isolated. In the absence of habitat corridors, genetic structure may develop and populations risk reductions in genetic diversity from increased genetic drift and inbreeding. Deforestation of the Cerrado biome of Brazil, particularly of the dry forests within the Paranã River Basin, has incrementally occurred since the 1970s and increased forest fragmentation within the region. We performed landscape genetic analyses of Pfrimer’s parakeet (Pyrrhura pfrimeri), a globally endangered endemic to the region, to determine if forest fragmentation patterns were associated with genetic structuring in this species. We used previously generated satellite imagery that identified the locations of Paranã River Basin forest fragments in 1977, 1993/94, and 2008. Behavioral data quantifying the affinity of Pfrimer’s parakeet for forest habitat was used to parameterize empirically derived landscape conductance surfaces. Though genetic structure was observed among Pfrimer’s parakeet populations, no association between genetic and geographic distance was detected. Likewise, least cost path lengths, circuit theory-based resistance distances, and a new measure of least cost path length complexity could not be conclusively associated with genetic structure patterns. Instead, a new quantity that encapsulated connection redundancy from the 1977 forest fragmentation data provided the clearest associations with pairwise genetic differentiation patterns (Jost’s D: r = 0.72, P = 0.006; F_ST: r = 0.741, P = 0.001). Our analyses suggest a 35-year or more lag between deforestation and its effect on genetic structure. Because 66 % of the Paranã River Basin has been deforested since 1977, we expect that genetic structure will increase substantially among Pfrimer’s Parakeet populations in the future, especially if fragmentation continues at its current pace.     

Landscape factors affecting the distribution of the great tit in fragmented urban forests of Seoul,South Korea

Seoul City, as the capital and largest metropolis of South Korea, has high population density, and its remaining forests are extremely fragmented as a result of intensive development. The purpose of this study is to analyze the distribution of the great tit (Parus major) and develop a habitat model. Tits have been known as forest birds that inhabit urban forests in Seoul City. A Seoul biotope map and land cover map were combined, and the urban forest areas were delineated on these maps. As factors affecting the distribution of the great tit, landscape indices were calculated by separating them into intrapatch indices, namely logged patch area (PA), area-weighted mean patch shape index (PSI), tree rate (TR), and tree area (TA), and interpatch indices, namely patch degree (PD), patch betweenness (PB), patch proximity (PP), and difference probability of connectivity (DPC), to analyze the internal properties of the patches and their connectivity by tit occurrence data. The results of a t test analyzing the differences of habitat variables by great tit presence/absence and distribution showed differences in PA (p < 0.05), PSI (p < 0.001), TR (p < 0.01), TA (p < 0.001), PD (p < 0.05), PB (p < 0.01), PP (p < 0.05), and DPC (p < 0.1). In the results of logistic regression modeling, in most cases, more than one model had ΔAICc less than 2.0, suggesting that multiple models may be the best model. In the comprehensive models, the TR, PB, and DPC metrics were the best predictors. Among all variables in the intrahabitat model, PSI was the best predictor of species occurrence. Within the interhabitat model, DPC was the best predictor and had a positive relationship with species occurrence, which is the most important of all the factors. In other words, the great tit is more likely to be found in a large circular forest patch than a small and long-shaped forest patch, and connectivity in the threshold distance is the most important factor in predicting great tit occurrence. These results suggest that ecological potential, not only “location potential” but also “supply potential,” should be considered in fragmented urban forests.     

Effect of conversion of sugarcane plantation to forest and pasture on soil carbon in Hawaii

It is well known that land use change can affect soil C storage of terrestrial ecosystems either by altering the biotic processes involved in carbon cycling or by altering abiotic processes such as carbon adsorption on soil minerals. Relatively few studies, however, have examined the dynamics of soil C pools after conversion of farmland to forest or pasture. We selected three pairs of secondary forests and pastures that originated from the same abandoned sugarcane (interspecific hybrids of Saccharum spp.) land in the wet tropics of Hawaii to examine whether forest or pasture converted from farmland is more effective in sequestering C in soils. We compared the soil C pool, soil chemistry, and stable C isotope ratios between the forests and pastures. We found that total soil C was greater (P?<?0.01) in forests than in the pastures 22 years after land conversion. The percentages of SOC₄ in the pastures were significantly higher than in the secondary forests in both soil layers. The percentages of SOC₃ in the pastures were lower than in the secondary forests in both soil layers. The net SOC₃ increase in the forest soils at 0–10 and 10–25 cm was 28.6?±?5.6 and 43.9?±?3.2 Mg ha^?1 while net SOC₄ increase in pasture soils at these respective depths was 18.8?±?2.2 and 26.1?±?2.7 Mg ha^?1. We found that the net increases of SOC₃ in both soil layers in the forest were greater (P?<?0.01) than the net increases of SOC₄ in the respective soil layers in the pasture. Aluminum saturation was greater (P?<?0.01) in the forests than the pastures in both soil layers. There was no difference in oxalate extractable Fe concentration between the forests and the pastures but oxalate extractable Al concentration in both soil layers was greater (P?<?0.05) in forests than the pastures. Our findings indicated that reforestation of abandoned sugarcane farmland in Hawaii is more effective in soil C increase and stabilization than conversion to pasture.     

Phenotypic profile of Aedes albopictus (Skuse) exposed to pyrethroid-based mat vaporizers and underlying detoxification mechanisms: A statewide report in Selangor,Malaysia

This study examines the biological efficacy of four mosquito mat vaporizers each containing different active ingredients: prallethrin with PBO, dimefluthrin, prallethrin, and d-allethrin. The glass chamber assay was used to evaluate their efficacy on Aedes albopictus (Skuse) (Diptera: Culicidae) from nine districts in Selangor, Malaysia. Aedes albopictus exhibited different knockdown rates, with 50% knockdown times, KT₅₀, varying from 1.19 to 2.00 min, 1.22 to 2.20 min, 1.39 to 5.85 min, and 1.39 to 1.92 min for prallethrin with PBO, dimefluthrin, prallethrin and d-allethrin, respectively. In general, all populations of Ae. albopictus were completely knocked down after exposure to all active ingredients except Hulu Selangor population, which showed 96.00% knockdown against d-allethrin. On the contrary, mortality rates were observed from 84.00–100.00%, 84.00–100.00%, 90.67–100.00% and 90.67–100.00% in populations tested with prallethrin with PBO, dimefluthrin, prallethrin and d-allethrin, respectively. Moreover, significant correlations between mortality rates of prallethrin with PBO vs dimefluthrin (r = 0.836, P = 0.003), prallethrin with PBO vs prallethrin (r = 0.760, P = 0.011), and prallethrin vs d-allethrin (r = 0.694, P = 0.026) were also observed, suggesting cross-resistance among pyrethroids. d-allethrin was found to be high in insecticidal activity, followed by prallethrin, prallethrin with PBO, and dimefluthrin. In consistent with mortality due to insecticide exposure, elevated levels of enzyme activities were also demonstrated in Sabak Bernam, Hulu Selangor, Gombak, Petaling, Hulu Langat and Klang populations.     

Litterfall production, decomposition and nutrient use efficiency varies with tropical forest types in Xishuangbanna, SW China: a 10-year study

Litterfall production, decomposition and nutrient use efficiency in three different tropical forest ecosystems in SW China were studied for 10 years. Annual mean litterfall production in tropical seasonal forest (TSF) (9.47?±?1.65 Mg ha^?1) was similar to that in man-made tropical forest (MTF) (9.23?±?1.29 Mg ha^?1) (P?>?0.05) but both were significantly lower than that in secondary tropical forest (STF) (12.96?±?1.71 Mg ha^?1) (P?<?0.05). The annual variation of litterfall was greater in TSF (17.4%, P?<?0.05) than in MTF (14.0%) or STF (13.2%). The annual mean decomposition rate of litterfall increased followed the order of MTF (2.72)?<?TSF (3.15)?<?STF (3.50) (P?<?0.05), which was not correlated with annual precipitation or annual mean temperature, but was rather related to litter quality. The nutrient use efficiency was found to be element-dependent and to vary significantly among the three forest types (P?<?0.05). These results indicate that litterfall production and decomposition rates in different tropical forest systems are related to plant species composition and are influenced strongly by coexisting species and their life stage (age) but less so by the species richness. Constructing multi-species and multistory man-made tropical forest is an effective way to enhance biological productivity and maintain soil nutrients on degraded tropical land.     

Oxidized Low Density Lipoprotein and Inflammation in Gout Patients

To analyze the levels of oxidized low density lipoprotein (ox-LDL) and inflammatory cytokines in the plasma of gout patients. The levels of ox-LDL, hypersensitive C-reactive protein (hs-CRP), interleukin-1β, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were measured in the plasma of 41 gout patients [28 in acute phase episode, 13 in intermittent phase (IP)], and in 40 healthy controls. The relationship between ox-LDL and inflammation was also explored by measuring the levels of several pro-inflammatory cytokines in the plasma. The plasma levels of ox-LDL, hs-CRP, IL-6 and TNF-α were significantly increased in patients with gout in the acute phase compared to those in the IP group and healthy controls (P < 0.05), but the levels of TGF-β were significantly lower in the acute phase group than in the IP group and healthy controls (P < 0.01). The levels of ox-LDL in the gout patients in the IP were significantly higher than those in healthy controls (P < 0.05). Correlation analysis indicated that the levels of ox-LDL were positively correlated with hs-CRP, IL-6 and TNF-α (r = 0.343, r = 0.386, r = 0.659, P < 0.01, respectively), but negatively correlated with TGF-β levels in patients in the acute phase (r = ?0.240, P < 0.05). The levels of ox-LDL in gout patients were significantly higher than those in healthy controls. The changes in ox-LDL levels may be associated with enhanced inflammation in gout patients.     

Relationships between stream habitat and breeding territory length of the Brown Dipper (Cinclus pallasii) in Taiwan

Dippers from the genus Cinclus are highly specialised predators on aquatic invertebrates, and occupy linear territories along rivers where measurements of variations in quality are relatively straightforward. For these reasons, they are ideal model species in which to examine factors affecting territory size. In this paper, we investigated the influence of stream habitats on the territory length of the Brown Dipper (Cinclus pallasii) in Taiwan. The biomass of aquatic insects and other stream habitat variables were analyzed to determine their relationships with the territory length of Brown Dippers from November 1988 to May 1989. Compared with slow-moving waters, riffle areas contained significantly greater insect biomass (paired t test, t ₁₁ = 3.49, P < 0.01), of which trichopteran larvae contributed about 70%. Dippers spent more time foraging in riffles than in slow-moving waters. In addition, dippers preferred foraging in shallow riffles, but avoided deep, slow-moving waters (G = 62.53, df = 3, P < 0.001). Territory length (1,045 ± 165 m [SE], n = 14) was negatively related to proportion of riffles (r ² = 0.5715, P < 0.01), total aquatic insect biomass (r ² = 0.5840, P < 0.01), and altitude (r ² = 0.7176, P < 0.001). In factor analysis, four factors were extracted from the 14 stream variables. However, only factor 1 was significantly related to territory length (r ² = 0.5207, P < 0.01). Factor 1 explained 42.8% of the total variance and collectively revealed the importance of high food abundance. In other words, Brown Dipper territories were the shortest along high-altitude streams with abundant riffles, fewer pools and abundant aquatic insects. These results indicate that abundant supply of accessible invertebrate prey is the most important factor affecting the territory length of Brown Dippers. This is consistent with Cinclus species elsewhere, and reveals the importance of clean, productive river ecosystems.     

Studies on the breeding habitats of the vector mosquito Anopheles baimai and its relationship to malaria incidence in Northeastern region of India

Entomological survey was conducted to know the breeding habitat preference of the forest breeder malaria vector Anopheles baimaii, known earlier as An. dirus species D in the northeastern region of India. Breeding potential of the vector in forest areas was found to be high in water stored in jungle pool (69.84%) followed by elephant footprints with clear water (39.13%) and with turbid water (26.19%), whereas in forest fringe areas, the vector breeding was more prominent in elephant footprints: 65.11% in clear water and 62.5% in turbid water. Although other habitats had shown only low breeding of the vector, all types of habitats were positively correlated with malaria occurrence. Cattle hoof marks (r = 0.998) and elephant footprint (turbid; r = 0.999) explained nearly the same amount of variance. It was observed that deforestation as well as elephant habitat-type destruction had engendered man–elephant conflicts intensively in fringe areas. Seasonal abundance pattern of this vector was found to vary in forest and forest fringe areas in relation to different habitats. Seasonal abundance of An. baimaii was significantly different in different habitats. The Tukey post hoc comparisons indicated that the abundance of An. baimaii in different habitats was significantly higher (P < 0.05) in monsoon season than that of premonsoon and postmonsoon seasons. No significant difference was observed between premonsoon and postmonsoon seasons. The findings therefore will eventually help to predict transmission of malaria in targeted area and in formulating an improved malaria control program in the northeastern region of India.     

Evidence for consumer regulation of biofilm–nutrient interactions among hardwater streams (Pennsylvania, USA)

Experimental studies evaluating the simultaneous effects of consumers, nutrients, and other biotic/abiotic factors on intact, natural food webs are rare, particularly among ecosystems of varying trophic conditions. We conducted a series of in situ studies that used nutrient-diffusing substrata with nitrogen (N) and phosphorus (P) concentrations in a full factorial design in three temperate, limestone streams in Pennsylvania across a trophic gradient (mesotrophic, eutrophic, and hypereutrophic streams). We assessed differences in algal and macroinvertebrate biomass, taxonomic composition, and functional groups relative to amended nutrients across the trophic gradient; as such, these results facilitated predictions about regulators of food web structure. All factors varied significantly among the streams (e.g., algal biomass P = 0.005, macroinvertebrate biomass P < 0.001, algal diversity P = 0.006, macroinvertebrate diversity P < 0.001, algal group P < 0.001, macroinvertebrate guilds P < 0.001); the streams, however, did not exhibit simple responses to nutrient amendment. Algal and macroinvertebrate biomass and diversity responded greatest in the mesotrophic stream while grazing seemed to be a strong factor preventing algal nutrient response in the eutrophic and hypereutrophic streams. Brillouin’s Evenness Index was most influenced by nutrient amendment (nutrient effect on algae and macroinvertebrates P = 0.021). As such, we concluded that biomass and diversity were mediated by complexity within intermediate trophic levels.     

Identifying Morphological and Mechanical Traits Associated with Stem Lodging in Bioenergy Sorghum (<Emphasis Type="Italic">Sorghum bicolor</Emphasis>)

Stem lodging in Sorghum is a major agronomic problem that has far-reaching economic consequences. More rapid and reliable advances in stem lodging resistance could be achieved through development of selective breeding tools that are not dependent on post hoc data or dependent on abiotic or biotic environmental factors. Our objective was to use sorghum to examine how mechanical stability is achieved and lost, and to provide insights into the development of a rapid and reliable phenotyping approach. The biomechanical properties of the stems of six bioenergy sorghum genotypes were investigated using a three-point bending test protocol. Important morphometric data were also collected, and previously collected lodging scores were used to associate with morphological and mechanical traits. Nodes were two to three-folds stronger, stiffer, and more rigid than internodes. In general, internodes were numerically weakest and more rigid between internodes 3 and 6, corresponding to the area where higher stem lodging is observed. Internode strength was negatively correlated with diameter (r = ?0.77, P < 0.05) and volume (r = 0.96, P < 0.01), while stem lodging was positively correlated with flexural rigidity (r = 0.85, P < 0.05) and volume (r = 0.78, P < 0.05). The analysis revealed key functional traits that influence the mode and location of stem lodging. Moreover, these results indicate the potential of these methods as a selective breeding tool for indirect selection of stem lodging resistance in bioenergy sorghum.     

Regional chronologies of <Emphasis Type="Italic">Cedrela</Emphasis><Emphasis Type="Italic">fissilis</Emphasis> and <Emphasis Type="Italic">Cedrela angustifolia</Emphasis> in three forest types and their relation to climate

Key message

Although tree-ring chronologies of Cedrela fissilis and Cedrela angustifolia showed a common climatic signal, local conditions influence growth, suggesting that forest guidelines should be appropriate to the species and context.

Abstract

Cedrela species are highly valued because of the quality of their timber. Understanding the behaviour of each different Cedrela species and their ecology is of importance to ensuring that forest harvesting and management do not endanger the survival of natural populations. These species grow in a wide range of environmental gradients and different types of forests in Bolivia. This study used dendrochronological methods to analyse growth–precipitation relationships of two Cedrela species coming from three locations with different environmental conditions: dry Chiquitano (Concepción), Chiquitano transitional Amazonian (Guarayos), and Bolivian-Tucuman montane forests (Postrervalle). The rainy season in all locations runs from October to April and the dry season runs from May to September. Twelve Cedrela fissilis specimens were sampled from dry Chiquitano, 11 Cedrela fissilis specimens from Chiquitano transitional Amazonian, and 30 Cedrela angustifolia specimens from Bolivian-Tucuman montane forests. The samples were crossdated and exhibited a common signal between trees from three sites, despite tree rings from the Chiquitano transitional Amazonian forest being narrower and displaying blurred bands of parenchyma in the boundaries. Significant inter-series correlation was found for the C. fissilis species series from dry Chiquitano with r = 0.261 (p < 0.01) and Chiquitano transitional Amazonian forests with r = 0.284 (p < 0.01), and for Cedrela angustifolia from Bolivian-Tucuman montane forests with r = 0.374 (p < 0.01). Mean annual growth was 2.07, 1.92, and 2.82 mm year^?1 at the three sites, respectively. Cedrela species from dry Chiquitano and Bolivian-Tucuman montane forests were sensitive to precipitation from October to April of the current growth year (wettest season) and to low temperatures from May to July of the current growth year (driest season). Samples from Chiquitano transitional Amazonian were more sensitive to precipitation during late rainy season (March, April, and May of the current growth year) and high temperatures during the rainy months (November–December). Growth differences between sites and species in response to climate variations and local conditions should be taken into account and handled with different forest management guidelines.

     

Is high prevalence of vitamin D deficiency a correlate for attention deficit hyperactivity disorder?

The aim of the study was to determine the association between vitamin D and attention deficit hyperactivity disorder (ADHD), and difference in the level of vitamin D in ADHD children and control. This a case–control study carried out in school health and primary health care clinics. A total of 1,331 children and adolescents who were diagnosed with ADHD based on clinical criteria and standardized questionnaires were enrolled in this study and were matched with 1,331 controls, aged 5–18 years old. Data on body mass index (BMI), clinical biochemistry variables including serum 25-hydroxyvitamin D were collected. The study found significant association between ADHD and vitamin D deficiency after adjusting for BMI and sex (adj. OR 1.54; 95 % CI 1.32–1.81; P < 0.001). Majority of the ADHD children were in the age group 5–10 years (40.7 %), followed by 11–13 years (38.4 %). The proportion of BMI <85th percentile was significantly over represented in ADHD group as compared to healthy control (87.8 vs. 83 %; P < 0.001, respectively), while on the other hand, BMI >95th percentile was over represented in the control than ADHD group (7.6 vs. 4.6 %; P < 0.001, respectively). Mean values of vitamin D (ng/mL) were significantly lower in ADHD children (16.6 ± 7.8) than in healthy children (23.5 ± 9.0) (P < 0.001). There was significant correlation between vitamin D deficiency and age (r = ?0.191, P = 0.001); calcium (r = 0.272, P = 0.001); phosphorous (r = 0.284, P = 0.001); magnesium (r = 0.292, P = 0.001); and BMI (r = 0.498, P = 0.001) in ADHD children. The vitamin D deficiency was higher in ADHD children compared to healthy children.     

Invertebrate feeding and emergence timing vary among streams along a gradient of riparian forest composition

1. The quality of allochthonous organic matter influences the transfer of energy and nutrients through recipient food webs. We investigated the effects of variation in the composition of riparian forests (deciduous, mixed, coniferous) on the elemental imbalance between basal resources and consumers in streams, on consumer feeding and on potential feedbacks to riparian systems via emergent aquatic insects. 2. We tested for differences in elemental stoichiometry (carbon/nitrogen/phosphorus; C/N/P) and stable isotopes (?¹³C and ?¹⁵N) between deciduous (red alder, Alnus rubra) and coniferous litter (western hemlock, Tsuga heterophylla) and among abundant stream invertebrates from streams draining different riparian forests (deciduous, mixed, coniferous). We then assessed shredder feeding preferences (of the trichopteran, Lepidostoma unicolor) for litter incubated in streams with these different forest types and quantified differences in emergence of aquatic and semiaquatic insects among streams. 3. Both initial (non‐incubated) and stream‐incubated A. rubra litter had lower C/N and C/P and were more depleted in ?¹³C and more enriched in ?¹⁵N, than T. heterophylla litter. The stoichiometry of invertebrate tissue did not vary significantly among taxa or with riparian forest composition. A predator (the plecopteran Chloroperlidae) and a collector‐gatherer (the ephemeropteran Paraleptophlebia gregalis) from mixed and coniferous forest streams were more enriched in ?¹³C and ?¹⁵N isotopes than those from deciduous streams, suggesting that low availability of palatable, N‐rich A. rubra litter may constrain energy flow and nutrient fluxes up through the food web in systems with little or no A. rubra. 4. Consumption of A. rubra litter by L. unicolor was most rapid when the litter had been incubated in streams draining deciduous forests, whereas consumption of T. heterophylla litter was not influenced by the composition of the riparian forest. 5. Peak insect emergence from coniferous forest streams occurred 1 month earlier and at 2–3× higher density than from mixed and deciduous‐forest streams, but total biomass of emerging insects throughout the study period was not different between forest types. Assemblages of emerging insects were different between deciduous and coniferous forest streams, and taxon richness and diversity were nearly 2× greater from deciduous than from coniferous forest streams. 6. Forest composition influences stream invertebrate feeding and could have reciprocal feedbacks onto riparian systems via altered insect emergence.     

Circulating microparticles in patients with coronary heart disease and its correlation with interleukin-6 and C-reactive protein

Microparticles (MPs) are vesicles released from activated or apoptotic cells. MP derive from various cells, most notably platelets, but also leucocytes, lymphocytes, erythrocytes, and endothelial cells. The aim of this study was to investigate endothelial MP (EMP), platelet MP (PMP), lymphocyte MP and monocyte MP and TF-positive MPs (TF⁺ MPs) in patients with coronary heart disease (CHD), and to evaluate the correlation of these MPs with Interleukin-6 (IL-6) and C-reactive protein (CRP). Different cell-derived MPs and TF⁺ MPs were analyzed by flow cytometry in 40 patients with myocardial infarction (MI), 30 unstable angina (UA), 20 stable angina (SA) and 20 healthy individuals, and IL-6 and CRP were determined by ELISA and special protein analyzer, respectively. Compared with SA and control, EMP and PMP was significantly elevated in MI and UA (P < 0.001), and TF⁺ MPs was significantly elevated in MI and UA (P < 0.001). EMP and PMP correlated with IL-6 (r = 0.822, P < 0.001 and r = 0.567, P < 0.001; respectively) or CRP level (r = 0.597, P < 0.001 and r = 0.66, P < 0.001; respectively). Different cell-derived MPs in CHD may indicate the different pathophysiological changes in vessels, and MPs may both participate in the development of thrombosis and enhance the vascular inflammation.     

Effects of nitrogen additions on above- and belowground carbon dynamics in two tropical forests

Anthropogenic nitrogen (N) deposition is increasing rapidly in tropical regions, adding N to ecosystems that often have high background N availability. Tropical forests play an important role in the global carbon (C) cycle, yet the effects of N deposition on C cycling in these ecosystems are poorly understood. We used a field N-fertilization experiment in lower and upper elevation tropical rain forests in Puerto Rico to explore the responses of above- and belowground C pools to N addition. As expected, tree stem growth and litterfall productivity did not respond to N fertilization in either of these N-rich forests, indicating a lack of N limitation to net primary productivity (NPP). In contrast, soil C concentrations increased significantly with N fertilization in both forests, leading to larger C stocks in fertilized plots. However, different soil C pools responded to N fertilization differently. Labile (low density) soil C fractions and live fine roots declined with fertilization, while mineral-associated soil C increased in both forests. Decreased soil CO₂ fluxes in fertilized plots were correlated with smaller labile soil C pools in the lower elevation forest (R² = 0.65, p < 0.05), and with lower live fine root biomass in the upper elevation forest (R² = 0.90, p < 0.05). Our results indicate that soil C storage is sensitive to N deposition in tropical forests, even where plant productivity is not N-limited. The mineral-associated soil C pool has the potential to respond relatively quickly to N additions, and can drive increases in bulk soil C stocks in tropical forests.     

Iron toxicity mediated by oxidative stress enhances tissue damage in an animal model of diabetes

Although iron is a first-line pro-oxidant that modulates clinical manifestations of various systemic diseases, including diabetes, the individual tissue damage generated by active oxidant insults has not been demonstrated in current animal models of diabetes. We tested the hypothesis that oxidative stress is involved in the severity of the tissues injury when iron supplementation is administered in a model of type 1 diabetes. Streptozotocin (Stz)-induced diabetic and non-diabetic Fischer rats were maintained with or without a treatment consisting of iron dextran ip at 0.1 mL day^?1 doses administered for 4 days at intervals of 5 days. After 3 weeks, an extensive increase (p < 0.001) in the production of reactive oxygen species (ROS) in neutrophils of the diabetic animals on iron overload was observed. Histological analysis revealed that this treatment also resulted in higher (p < 0.05) tissue iron deposits, a higher (p < 0.001) number of inflammatory cells in the pancreas, and apparent cardiac fibrosis, as shown by an increase (p < 0.05) in type III collagen levels, which result in dysfunctional myocardial. Carbonyl protein modification, a marker of oxidative stress, was consistently higher (p < 0.01) in the tissues of the iron-treated rats with diabetes. Moreover, a significant positive correlation was found between ROS production and iron pancreas stores (r = 0.42, p < 0.04), iron heart stores (r = 0.54, p < 0.04), and change of the carbonyl protein content in pancreas (r = 0.49, p < 0.009), and heart (r = 0.48, p < 0.02). A negative correlation was still found between ROS production and total glutathione content in pancreas (r = ?0.50, p < 0.03) and heart (r = ?0.45, p < 0.04). In conclusion, our results suggest that amplified toxicity in pancreatic and cardiac tissues in rats with diabetes on iron overload might be attributed to increased oxidative stress.     

Effect of metabolic syndrome risk factors and MMP-2 genetic variations on circulating MMP-2 levels in childhood obesity

Matrix metalloproteinase-2 is involved in the development of the adipose tissue, and associated with cardiovascular diseases. Metabolic risk factors (MRFs) and functional polymorphisms in the MMP-2 gene may affect its expression and activity. We investigated whether traditional MRFs and two MMP-2 gene polymorphisms (C^?1306T; rs243865, and C^?735T; rs2285053) affect circulating MMP-2 levels in children and adolescents, and whether MMP-2 polymorphisms and/or haplotype are associated with susceptibility to childhood obesity. We studied 114 healthy controls, 43 obese, and 83 obese with ≥3 MRFs children and adolescents. Genotypes were determined by Taqman allele discrimination assay and real-time PCR. Plasma MMP-2 was measured using zymography. We found positive correlations between MMP-2 concentrations and mean blood pressure in all children and adolescents group (r = 0.132; P < 0.05) and in obese children and adolescents (r = 0.247; P < 0.01). We found that the CC genotype for the C^?1306T polymorphism was more common in subjects with higher MMP-2 concentrations in controls (P = 0.003) and in the obese group (P = 0.013). The CT genotype (OR = 0.40; P < 0.01) and the T allele (OR = 0.48; P < 0.01) for the C^?735T polymorphism were less common in obese children and adolescents than in controls. The haplotypes distribution did not show significant differences between control and obese (P > 0.05). Ours findings show that blood pressure is associated with circulating MMP-2 concentrations, and that the CC genotype for the C^?1306T polymorphism was more common subjects (controls and obese) with higher MMP-2 concentrations, whereas the CT genotype and the T allele for the C^?735T polymorphism are less common in obesity.     

Nitrogen-15 signals of leaf-litter-soil continuum as a possible indicator of ecosystem nitrogen saturation by forest succession and N loads

Understanding forest carbon cycling responses to atmospheric N deposition is critical to evaluating ecosystem N dynamics. The natural abundance of ¹⁵N (??¹⁵N) has been suggested as an efficient and non-invasive tool to monitor N pools and fluxes. In this study, three successional forests in southern China were treated with four levels of N addition. In each treatment, we measured rates of soil N mineralization, nitrification, N₂O emission and inorganic N leaching as well as N concentration and ?? ¹⁵N of leaves, litters and soils. We found that foliar N concentration and ??¹⁵N were higher in the mature broadleaf forest than in the successional pine or mixed forests. Three-year continuous N addition did not change foliar N concentration, but significantly increased foliar ?? ¹⁵N (p < 0.05). Also, N addition decreased the ?? ¹⁵N of top soil in the N-poor pine and mixed forests and significantly increased that of organic and mineral soils in N-rich broadleaf forests (p < 0.05). In addition, the soil N₂O emission flux and inorganic N leaching rate increased with increasing N addition and were positively correlated with the ¹⁵N enrichment factor (?? _p/s) of forest ecosystems. Our study indicates that ?? ¹⁵N of leaf, litter and soil integrates various information on plant species, forest stand age, exogenous N input and soil N transformation and loss, which can be used to monitor N availability and N dynamics in forest ecosystems caused by increasing N deposition in the future.     

A comparison of the population genetic structure of parasitic Viscum album from two landscapes differing in degree of fragmentation

Parasite populations do not necessarily conform to expected patterns of genetic diversity and structure. Parasitic plants may be more vulnerable to the negative consequences of landscape fragmentation because of their specialized life history strategies and dependence on host plants, which are themselves susceptible to genetic erosion and reduced fitness following habitat change. We used AFLP genetic markers to investigate the effects of habitat fragmentation on genetic diversity and structure within and among populations of hemiparasitic Viscum album. Comparing populations from two landscapes differing in the amount of forest fragmentation allowed us to directly quantify habitat fragmentation effects. Populations from both landscapes exhibited significant isolation-by-distance and sex ratios biased towards females. The less severely fragmented landscape had larger and less isolated populations, resulting in lower levels of population genetic structure (F _ST = 0.05 vs. 0.09) and inbreeding (F _IS = 0.13 vs. 0.27). Genetic differentiation between host-tree subpopulations was also higher in the more fragmented landscape. We found no significant differences in within-population gene diversity, percentage of polymorphic loci, or molecular variance between the two regions, nor did we find relationships between genetic diversity measures and germination success. Our results indicate that increasing habitat fragmentation negatively affects population genetic structure and levels of inbreeding in V. album, with the degree of isolation among populations exerting a stronger influence than forest patch size.     

Temporal fragmentation of a critically endangered forest ecosystem

Landscape change and habitat fragmentation is increasingly affecting forests worldwide. Assessments of patterns of spatial cover in forests over time can be critical as they reveal important information about landscape condition. In this study, we assessed landscape patterns across the Mountain Ash (Eucalyptus regnans) and Alpine Ash (Eucalyptus delegatensis) forests in the Central Highlands of Victoria between 1999 and 2019. These forests have experienced major disturbance over the past 20 years through a major fire (in 2009) and extensive industrial logging. We found that around 70% and 65% of the Mountain Ash and Alpine Ash forest areas, respectively, were either disturbed or within 200 m of a disturbed area. Inclusion of planned logging increased these disturbance categories to 72% and 70%, respectively. We also found that the isolation of Mountain Ash core areas (patches of undisturbed forest >1000 ha) increased significantly (P < 0.05) over our study period, with the proximity between disturbed areas conversely increasing significantly (P < 0.05). This means that continued and planned disturbance through industrial logging will have an amplified adverse effect on remaining undisturbed ash forest patches, which will become smaller and more dispersed across the landscape.