An Evaluation of Plotless Sampling Using Vegetation Simulations and Field Data from a Mangrove Forest

In vegetation science and forest management, tree density is often used as a variable. To determine the value of this variable, reliable field methods are necessary. When vegetation is sparse or not easily accessible, the use of sample plots is not feasible in the field. Therefore, plotless methods, like the Point Centred Quarter Method, are often used as an alternative. In this study we investigate the accuracy of different plotless sampling methods. To this end, tree densities of a mangrove forest were determined and compared with estimates provided by several plotless methods. None of these methods proved accurate across all field sites with mean underestimations up to 97% and mean overestimations up to 53% in the field. Applying the methods to different vegetation patterns shows that when random spatial distributions were used the true density was included within the 95% confidence limits of all the plotless methods tested. It was also found that, besides aggregation and regularity, density trends often found in mangroves contribute to the unreliability. This outcome raises questions about the use of plotless sampling in forest monitoring and management, as well as for estimates of density-based carbon sequestration. We give recommendations to minimize errors in vegetation surveys and recommendations for further in-depth research.     

Overexpression of a chitinase gene in transgenic peanut confers enhanced resistance to major soil borne and foliar fungal pathogens

A chitinase gene from rice (Rchit) was introduced into three varieties of peanut through Agrobacterium-mediated genetic transformation resulting in 30 transgenic events harboring the Rchit gene. Stable integration and expression of the transgenes were confirmed using PCR, RT-PCR and Southern blot analysis. Progeny derived from selfing of the primary transgenic events revealed a Mendelian inheritance pattern (3:1) for the transgenes. The chitinase activity in the leaves of the transgenic events was 2 to 14-fold greater than that in the non-transformed control plants. Seeds of most transgenic events showed 0–10 % A. flavus infection during in vitro seed inoculation bioassays. Transgenic peanut plants evaluated for resistance against late leaf spot (LLS) and rust using detached leaf assays showed longer incubation, latent period and lower infection frequencies when compared to their non-transformed counterparts. A significant negative correlation existed between the chitinase activity and the frequency of infection to the three tested pathogens. Three progenies from two transgenic events displayed significantly higher disease resistance for LLS, rust and A. flavus infection and are being advanced for further evaluations under confined field conditions to confirm as sources to develop peanut varieties with enhanced resistance to these fungal pathogens.     

Disentangling the effects of global climate and regional land-use change on the current and future distribution of mangroves in South Africa

The mangrove distribution in South Africa is fragmented and restricted to small forest patches occupying only 16 % of the estuaries within the current range. In this study we used species distribution models to test (1) whether the absence of mangrove forest and its species (Avicennia marina, Bruguiera gymnorrhiza and Rhizophora mucronata) within their current range is driven by climate or by climate combined with human or geomorphic perturbation and (2) how climate change may potentially affect the latitudinal limit of the mangrove forests and its species in South Africa. We used three modelling techniques (generalized linear models, generalized additive models and gradient boosting machines) and a set of three climate-based predictive variables (minimum air temperature of the coldest month, waterbalance and growing-degree days) combined separately with an index of human or geomorphic perturbation. Climate variables for the future projections were derived from two general circulation models driven by two socio-economic scenarios (A2a and B2a). Within the range of the mangrove forest, the fragmented distribution of the mangroves in South Africa was not explained by our set of climate variables alone. The index of human perturbations slightly improved the predictions but the index of geomorphic perturbation did not. Climate change will create climatically suitable sites for the mangrove forest and the two species A. marina and B. gymnorrhiza beyond their current limits, but model outcomes did not agree on the future potential distribution of R. mucronata. We were able to successfully predict range limits and to detect future climatically suitable sites beyond the current limits. Factors controlling mangrove distribution within its range are still to be identified although absences were partly explained by human perturbations.     

Somatoform disorders among patients attending walk-in clinics in Trinidad: prevalence and association with depression and anxiety

Objectives Somatoform disorders are common in international primary care settings, but have been little studied in the developing world. The objective of this study was to determine the prevalence of severe undifferentiated somatoform disorder, and its relationship to depression and anxiety, among patients attending walk-in clinics in Trinidad.Methods The study participants, who were all aged 18 years or older and attending walk-in clinics at 16 randomly selected health centres, were surveyed between May and August 2007 using the PRIME-MD questionnaire.Results There were 594 participants (the response rate was 92%), of whom 72.7% were female. Their ages ranged from 18 to 93 years, and 54.5% were over 50 years of age. In total, 37.2% were married and 25.9% were single. Indo-Trinidadians represented 43.1% and Afro-Trinidadians represented 36% of the study sample; 56.5% of the participants reported that their income was less than US$ 400 per month, and 65.7% were unemployed. At walk-in clinics in Trinidad, the estimated prevalence of severe undifferentiated somatoform disorder was 10.3% (95% CI: 7.86–12.74), that of hypochondriasis was 28.5% (95% CI: 24.9–32.1), and that of body dysmorphic disorder was 15.8% (95% CI: 11.9–18.7). Severe undifferentiated somatoform disorder was statistically significantly associated with gender and ethnicity but not with age, level of education, employment status or income. Chi-square testing found significant associations between the presence of severe undifferentiated somatoform disorder and both depression and anxiety (P < 0.05), between hypochondriasis and both anxiety and depression (P < 0.05), and between body dysmorphic disorder and depression (P < 0.05) but not anxiety. Regression analysis suggested that the demographic features that predicted severe undifferentiated somatoform disorder were being female or Indo-Trinidadian.Conclusions Walk-in clinics in Trinidad that serve older patients on a lower income have a high proportion of patients with somatoform disorders as measured by the PRIME-MD scale. These patients exhibit many features of anxiety and depression. These findings have implications for medical training and service delivery.     

A scale‐down mimic for mapping the process performance of centrifugation,depth and sterile filtration

In the production of biopharmaceuticals disk‐stack centrifugation is widely used as a harvest step for the removal of cells and cellular debris. Depth filters followed by sterile filters are often then employed to remove residual solids remaining in the centrate. Process development of centrifugation is usually conducted at pilot‐scale so as to mimic the commercial scale equipment but this method requires large quantities of cell culture and significant levels of effort for successful characterization. A scale‐down approach based upon the use of a shear device and a bench‐top centrifuge has been extended in this work towards a preparative methodology that successfully predicts the performance of the continuous centrifuge and polishing filters. The use of this methodology allows the effects of cell culture conditions and large‐scale centrifugal process parameters on subsequent filtration performance to be assessed at an early stage of process development where material availability is limited. Biotechnol. Bioeng. 2016;113: 1934–1941. © 2016 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc.     

Gastroretentive Matrix Tablets of Boswellia Oleogum Resin: Preparation,Optimization, <Emphasis Type="Italic">In Vitro</Emphasis> Evaluation,and Cytoprotective Effect on Indomethacin-Induced Gastric Ulcer in Rabbits

Currently available anti-ulcer drugs suffer from serious side effects which limited their uses and prompted the need to search for a safe and efficient new anti-ulcer agent. Boswellia gum resin (BR) emerged as a safe, efficient, natural, and economic potential cytoprotective agent. Thus, it is of medical importance to develop gastroretentive (GR) formulations of BR to enhance its bioavailability and anti-ulcer efficacy. Early attempts involved the use of organic solvents and non-applicability to large-scale production. In this study, different tablet formulations were prepared by simple direct compression combining floating and bioadhesion mechanisms employing hydroxypropyl methylcellulose (HPMC), sodium carboxymethyl cellulose (SCMC), pectin (PC), and/or carbopol (CP) as bioadhesive polymers and sodium bicarbonate (SB) as a gas former. The prepared tablets were subjected for assessment of swelling, floating, bioadhesion, and drug release in 0.1 N HCl. The optimized GR formulation was examined for its protective effect on the gastric ulcer induced by indomethacin in albino rabbits compared with lactose tablets. The obtained results disclosed that swelling, floating, bioadhesion, and drug release of the GR tablets of BR depend mainly on the nature of the matrix and the ratio of polymer combinations. Moreover, a combination of SCMC-CP in a ratio of 2:1 (SCP21) exhibited desirable floating, bioadhesion, swelling, and extended drug release. Also, a 6-h pretreatment with SCP21 tablets decreased the severity of inflammation and number of bleeding spots among ulcer-induced rabbits in comparison to those treated with lactose tablets.