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1.
Mangroves are among the most carbon-dense ecosystems worldwide. Most of the carbon in mangroves is found belowground, and root production might be an important control of carbon accumulation, but has been rarely quantified and understood at the global scale. Here, we determined the global mangrove root production rate and its controls using a systematic review and a recently formalised, spatially explicit mangrove typology framework based on geomorphological settings. We found that global mangrove root production averaged ~770 ± 202 g of dry biomass m−2 year−1 globally, which is much higher than previously reported and close to the root production of the most productive tropical forests. Geomorphological settings exerted marked control over root production together with air temperature and precipitation (r2 ≈ 30%, p < .001). Our review shows that individual global changes (e.g. warming, eutrophication, drought) have antagonist effects on root production, but they have rarely been studied in combination. Based on this newly established root production rate, root-derived carbon might account for most of the total carbon buried in mangroves, and 19 Tg C lost in mangroves each year (e.g. as CO2). Inclusion of root production measurements in understudied geomorphological settings (i.e. deltas), regions (Indonesia, South America and Africa) and soil depth (>40 cm), as well as the creation of a mangrove root trait database will push forward our understanding of the global mangrove carbon cycle for now and the future. Overall, this review presents a comprehensive analysis of root production in mangroves, and highlights the central role of root production in the global mangrove carbon budget.  相似文献   
2.
A study of primordial germ cells (PGC) of Amphibia Anura was carried out after treatment of sections by different fluorescein isothiocyanate conjugated lectins (FITC-lectins). Specific labelling on the PGC is obtained with lectins, the activity of which is inhibited by D-galactose or N-acetyl-galactosamine. These osidic groups appear to be located more specifically on the PGC. The same labelling pattern is not obtained with lectins possessing major affinity for mannose, glucose, fucose and N-acetyl-glucosamine. Furthermore, changes in labelling pattern are observed during migration of PGC. It is suggested that D-galactose and N-acetyl-galactosamine might be related to membrane activity of PGC during migration. Ultrastructural study of the visualization of cell surface carbohydrates supplies some information on the localisation of these lectins receptors.  相似文献   
3.
Although a growing number of studies suggest interactions between Schistosoma parasites and viral infections, the effects of schistosome infections on the host response to viruses have not been evaluated comprehensively. In this systematic review, we investigated how schistosomes impact incidence, virulence, and prevention of viral infections in humans and animals. We also evaluated immune effects of schistosomes in those coinfected with viruses. We screened 4,730 studies and included 103. Schistosomes may increase susceptibility to some viruses, including HIV and Kaposi’s sarcoma-associated herpesvirus, and virulence of hepatitis B and C viruses. In contrast, schistosome infection may be protective in chronic HIV, Human T-cell Lymphotropic Virus-Type 1, and respiratory viruses, though further research is needed. Schistosome infections were consistently reported to impair immune responses to hepatitis B and possibly measles vaccines. Understanding the interplay between schistosomes and viruses has ramifications for anti-viral vaccination strategies and global control of viral infections.  相似文献   
4.
Monte Carlo simulations and TLD dosimetry have been performed to determine the dose distributions along the central axis of the 12 mm COMS eye plaques loaded with IRA1-103Pd seeds. Several simulations and measurements have been employed to investigate the effect of Silastic insert and air in front of the eye on dosimetry results along the central axis of the plaque and at some critical ocular structures. Measurements were performed using TLD-GR200A circular chip dosimeters in a PMMA eye phantom. The central axis TLD chips locations were arranged in one central column of eye phantom, in 3 mm intervals. The off-axis TLD chips locations were arranged in three off-axis columns around the central axis column. Version 5 of the MCNP code was also used to evaluate the dose distribution around the plaque. The presence of the Silastic insert results in dose reduction of 14% at 5 mm; also about 7% dose reduction appears at the interface point, due to the air presence and lack of the scattering condition. The overall dosimetric parameters for the COMS eye plaque loaded with new palladium seeds are similar to a commercial widely used seed such as Theragenics200. As the dose calculations under TG-43 assumptions do not consider the effect of the plaque backing and Silastic insert for accurate dosimetry, it's suggested to apply the effect of the eye plaque materials and air on dosimetry results along the central axis of the plaque and at some critical ocular structures.  相似文献   
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6.

Objectives

To prepare for future HIV prevention trials, we conducted prospective cohort studies among women working in food and recreational facilities in northern Tanzania. We examined the prevalence and incidence of HIV and HSV-2, and associated risk factors.

Methods

Women aged 18–44 years working in food and recreational facilities were screened to determine their eligibility for the studies. Between 2008–2010, HIV-negative women were enrolled and followed for 12 months. At enrolment and 3-monthly, we collected socio-demographic and behavioural data, and performed clinical examinations for collection of biological specimens that were tested for reproductive tract infections. Risk factors for HIV and HSV-2 incidence were investigated using Poisson regression models.

Results

We screened 2,229 and enrolled 1,378 women. The median age was 27 years (interquartile range, IQR 22, 33), and median duration working at current facility was 2 years. The prevalences of HIV at screening and HSV-2 at enrolment were 16% and 67%, respectively. Attendance at the 12-month visit was 86%. HIV and HSV-2 incidence rates were 3.7 (95% confidence interval, CI: 2.8,5.1) and 28.6 (95% CI: 23.5,35.0)/100 person-years, respectively. Women who were separated, divorced, or widowed were at increased risk of HIV (adjusted incidence rate ratio, aRR = 6.63; 95% CI: 1.97,22.2) and HSV-2 (aRR = 2.00; 95% CI: 1.15,3.47) compared with married women. Women reporting ≥3 partners in the past 3 months were at higher HIV risk compared with women with 0–1 partner (aRR = 4.75; 95% CI: 2.10,10.8), while those who had reached secondary education or above were at lower risk of HSV-2 compared with women with incomplete primary education (aRR = 0.42; 95% CI: 0.22,0.82).

Conclusions

HIV and HSV-2 rates remain substantially higher in this cohort than in the general population, indicating urgent need for effective interventions. These studies demonstrate the feasibility of conducting trials to test new interventions in this highly-mobile population.  相似文献   
7.
Elasmobranchs are an important catch component in Tunisian artisanal fisheries. Generally, species‐specific information is largely unavailable for artisanal fisheries; an increase in knowledge thereof is essential to ensure proper management of these species. The study analyzed the gillnet fishery elasmobranch catches in the Gulf of Gabès, whereby 45 fishing trips were conducted from April to June 2007 and 2008 for the capture of a total of six species: three Rajiformes and three Carchariniformes. Rhinobatos cemiculus was the most important species (52%; 4.588 ind km?2 net per day). Among shark species, Mustelus mustelus was the most important (66.8%; 2.21 ind km?2 net per day). Discards represented 6.87% of total catch in weight and 14.28% in number of specimens caught. Size composition of captures varied by species, but usually mature, mainly gravid females were abundant. Further investigations are needed to obtain more information on such fragile species for the development of protective measures.  相似文献   
8.
A molecular study was carried out to incriminate sand fly vectors of cutaneous leishmaniasis (CL) in rural areas of Sarakhs district, Khorassane-Razavi Province, northeastern Iran, in 2011. Sand flies of Sergentomyia with three species and Phlebotomus with six species respectively comprised 73.3% and 26.7% of the specimens. Phlebotomus papatasi was the most common Phlebotomine species in outdoor and indoor resting places. Leishmania infection was found at least in 17 (22%) specimens including Ph. papatasi (n = 9 pool samples), Phlebotomus caucasicus (n = 6), Phlebotomus alexandri (n = 1), and Sergentomyia sintoni (n = 1). The parasites were found comprised Leishmania major (n = 5), Leishmania turanica (n = 10), and Leishmania gerbilli (n = 4). Infection of Ph. papatasi with both L. major and L. turanica supporting the new suggestion indicating that it is not restricted only with L. major. Circulation of L. major by Ph. alexandri, and both L. gerbilli and L. turanica by Ph. caucasicus, in addition to previous data indicating the ability of Ph. alexandri to circulate Leishmania infantum and Leishmania donovani, and Ph. caucasicus to circulate L. major, suggests that these two species can be permissive vectors. The results suggest that Ph. papatasi and Ph. alexandri are the primary and secondary vectors of CL where circulating L. major between human and reservoirs, whereas Ph. caucasicus is circulating L. turanica and L. gerbilli between the rodents in the region.  相似文献   
9.
10.
Small‐scale fisheries are generally promoted as a sustainable alternative to large‐scale industrial fisheries. However, there is recent growing evidence that small‐scale fisheries may be the largest threat to marine species of conservation concern. The objective of this study was to evaluate the potential impact of the trammel net fishery on elasmobranchs in the Gulf of Gabès, Southern Tunisia. Data are based on 191 shrimp trammel net set (40 mm stretched mesh size) surveys conducted aboard commercial fishing vessels from May to July 2009. Five species of the small coastal elasmobranchs (Mustelus mustelus (Linnaeus, 1758), Mustelus punctulatus Risso 1827, Dasyatis pastinaca (Linnaeus, 1758), Dasyatis marmorata (Steindachner, 1892) and Torpedo torpedo (Linnaeus, 1758)) and two species from the large coastal shark (Carcharhinus plumbeus (Nardo, 1827) and Carcharhinus brevipinna (Müller & Henle, 1839)) were recognized as by‐catch in this fishery. Elasmobranch by‐catch was dominated by sharks (90.3%), smoothhound sharks Mustelus sp. being by far the most important (88.9%) and reflecting their abundance in the area; 58% of the sets caught at least one specimen, with 4.8 ± 1.3 caught per set. Captures were composed essentially of neonate and juvenile sharks, while the batoids were dominated by mature individuals. This study shows that shrimp trammel nets represent a considerable source of mortality for early life stages of elasmobranch species in the Gulf of Gabès. Additionally, there was a high density of neonates and small juvenile M. mustelus in the Sfax zone, suggesting that these nearshore waters are a nursery grounds for smoothhound sharks. Further research should focus on the incidents of by‐catch and evaluate the potential solutions to allow trammel net fisheries to coexist alongside the elasmobranch species.  相似文献   
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