Effect of exotic invasive old world climbing fern (lygodium microphyllum) on soil properties

Old World climbing fern (Lygodium microphyllum) has become one of the most serious ecological threats to the integrity of the greater Everglades ecosystem of south Florida. In this study, we analyzed the effects of Old World climbing fern on surfacesoil characteristics at invaded sites in Florida. We compared soil characteristics of six invaded and adjacent uninvaded plots at three different locations. Our results show that the fern can grow and thrive in a wide range of soil types and the impact on the soil was site specific with effects being more prominent in sites with low nutrient status. Additionally, there were significant differences in the soil nutrient status and microbial population in the invaded and uninvaded sites. Sites with Old World climbing fern had significantly higher nutrient concentrations that correlated with higher soil organic matter. Overall our results indicate that this exotic pest plant can potentially alter its below ground environment to its own benefit by enhancing the soil nutrient status by adding soil organic matter

Probabilistic Estimation of Corrosion Propagation Period for Prestressed Concrete Structures Exposed to Chlorides

The overall service life of concrete structures can be divided into corrosion initiation and corrosion propagation phases. The durations of these two phases depend on the chloride threshold (Clth) and corrosion rate (icorr), respectively, of the embedded steel reinforcement. Quantitative information on Clth and icorr of conventional steel reinforcement are available in literature. Now‑a‑days, the use of prestressed concrete elements are rapidly increasing and there is a dire need for estimating their service life. Quantitative information on the Clth and icorr of prestressing steel are required for this estimation. However, very limited quantitative information is available on these parameters. As such, the current practice is to assume that both conventional and prestressing steels have similar Clth and icorr – which might result in unrealistic estimations. This paper provides data on icorr obtained from a 9-month long experimental program. The icorr data was obtained using linear polarization resistance (LPR) tests on prestressing wire embedded in mortar. 10 specimens (made using the center king-wires obtained from 7-wire strands) were cast, cured, and subjected to a cyclic wet-dry exposure using 3.5 % sodium chloride solution. It is observed that the average value of icorr of prestressing steel exposed to chloride‑contaminated mortar is around 5.8 mA/cm2. The paper also provides the probabilistic estimations on corrosion propagation period, tp (defined as the time to crack after corrosion initiation) by substituting the measured icorr data into two models from literature [i.e., Morinaga (1990) and Wang and Zhao (1993)]. It is found that the estimated average tp for prestressed concrete systems are 5.4 and 9.7 years with large scatter. This paper also provides probabilistic estimations on tp for the prestressed concrete systems with 50, 65, and 80 mm cover depths

Description of a new species of Caridina H. M. Edwards from the hill streams of southern Western Ghats, Tamil Nadu, India

The paper describes a new species, Caridina mathiassi sp. nov., from the hill streams of Mahendragiri Estate, part of southern Western Ghats, Kanyakumari District, Tamil Nadu, India (8o 27’ 32.27" N and 77o 23’ 32.50" E) collected during summer months of 1999 and 2000. This species is abundant and closely related to Caridina jalihali Mariappan and Richard, 2006 and Caridina gurneyi Jalihal et al., 1984. The diagnosis of the species include: shrimps of genus Caridina having a moderately long rostrum with 11-20 dorsal (4-6 post-orbital) and 2-7 ventral teeth; telson not ending in a median spine but with 4-10 spinules at distal and 3-5 pairs of spines at dorsal regions; carpus of first pereiopod deeply excavated anteriorly; fourth pereiopod with merus having 2-4, carpus having 1 large and 3-5 small spines and dactylus ending in a sharp spine and 5-7 spinules; fifth pereiopod with merus having 2-4, carpus with 1 large and sometimes 3-4 small spines and dactylus having 30-40 spinules; endopod of first pleopod with long appendix interna subterminal, curved inwards; appendix masculina double the size of appendix interna or a little longer of male second pleopod; diaeresis of uropod with 16-22 spines; size of eggs ranging from 0.53-0.61 X 0.86-1.04 mm and fecundity ranging from 122-181

In vitro efficacy of fungal endophytes and silver pyrazolate against Raffaelea lauricola, causal agent of laurel wilt of avocado

The South Florida avocado industry is being severely impacted by laurel wilt disease. Laurel wilt disease of avocado is caused by the fungal pathogen, Raffaelea lauricola (RL) and is vectored by ambrosia beetle, Xyleborus glabratus. Treatments options are limited, economically not sustainable, and require reapplication fungicides every couple of years. There is a crucial need for developing multiple modes of control using novel biological and chemical agents. The ambrosia beetle associated pathogenic fungi are known to outcompete other microorganisms by taking advantage of ethanol produced by the pathogen and the stressed tree. Endophytes, which reside inside the host plant tissue are part of the plant microbiome represent source of new potential biological control agents. In this study, three ethanol tolerant endophytic fungal species, isolated from avocado bark, were evaluated using in vitro dual culture assay and colonization tube (packed with bark/sapwood shaving) against RL. The endophytic isolates Tricoderma crissum, Tricoderma simmonsii, Lasiodiplodia theobromae were found to be highly capable of suppressing the mycelial colony growth of RL. The results suggest that combined abilities of ethanol tolerance and competitive colonization can provide useful criteria for identifying potential biocontrol agents. In vitro anti-RL activity of silver pyrazolate compound was assessed in both agar and liquid medium. Silver pyrazolate at levels of 30 and 45 ppm were found to be highly effective against RL. Further in planta research is needed to study the effects of endophytic fungal isolates and silver pyrazolate to assess their potential as additional tools for management of laurel wilt

Performace of mango-ginger (Curcuma amada Roxb.) under different levels of shade

Field trials on the performance of mango-ginger (Curcuma amada) conducted at Vellayani (Kerala, India) for two seasons under varying levels of shade revealed that rhizome yield under open and 25 per cent shade were on par indicating that the crop is shade tolerant and is suitable for intercropping situations. &nbsp

Performace of mango-ginger (Curcuma amada Roxb.) under different levels of shade

Field trials on the performance of mango-ginger (Curcuma amada) conducted at Vellayani (Kerala, India) for two seasons under varying levels of shade revealed that rhizome yield under open and 25 per cent shade were on par indicating that the crop is shade tolerant and is suitable for intercropping situations. &nbsp

The Effect of Saltwater Stress on the Performance of Cherry Tomatoes

Rising sea levels and saltwater intrusion in aquifers pose significant challenges for South Florida agriculture, leading to increased groundwater salinity and potential crop losses. Utilizing salttolerant crop species presents a potential solution for saline soils and regions with active saltwater intrusion. However, the effects of soil salinization through groundwater alone remains less studied. This research investigates the impact of short-term, below-ground saltwater stress on the growth, survival, and overall health of commonly grown cherry tomatoes (Solanum lycopersicum). The objectives of the study are to: 1) determine the impact of saline groundwater on tomato plant health and 2) compare the nutrient content of soil and tomato plant tissue exposed to varying concentrations of saline water. Established cherry tomato plants were exposed to varying concentrations of NaCl solution, simulating saltwater intrusion into groundwater. Over 28 days, plant height, leaf chlorophyll levels, and disease occurrences were monitored. It was found that the NaCl treatments did not significantly affect cherry tomato performance under the parameters of height, chlorophyll levels, or leaf nutrition when compared to the control group. This study suggests that cherry tomatoes can tolerate short-term exposure to NaCl in groundwater. Further exploration of more intense salt stress conditions from groundwater could be beneficial for utilizing this crop in areas with saline soils or polluted groundwater. Identification of salt-tolerant cherry tomato varieties can provide alternative crop options for non-arable land affected by high soil salinity

Yeast Ssd1 is a non-enzymatic member of the RNase II family with an alternative RNA recognition interface

Ssd1, a conserved fungal RNA-binding protein, is important in stress responses, cell division and virulence. Ssd1 is closely related to Dis3L2 of the RNase II family of nucleases, but lacks catalytic activity and likely suppresses translation of bound mRNAs. Previous studies identified RNA motifs enriched in Ssd1-associated transcripts, yet the sequence requirements for Ssd1 binding are not defined. Here, we identify precise binding sites of Ssd1 on RNA using in vivo cross-linking and cDNA analysis. These sites are enriched in 5′ untranslated regions of a subset of mRNAs encoding cell wall proteins. We identified a conserved bipartite motif that binds Ssd1 with high affinity in vitro. Active RNase II enzymes have a characteristic, internal RNA binding path; the Ssd1 crystal structure at 1.9 Å resolution shows that remnants of regulatory sequences block this path. Instead, RNA binding activity has relocated to a conserved patch on the surface of the protein. Structure-guided mutations of this surface prevent Ssd1 from binding RNA in vitro and phenocopy Ssd1 deletion in vivo. These studies provide a new framework for understanding the function of a pleiotropic post-transcriptional regulator of gene expression and give insights into the evolution of regulatory and binding elements in the RNase II family

Leukocyte- and Platelet-Derived Microvesicle Interactions following In Vitro and In Vivo Activation of Toll-Like Receptor 4 by Lipopolysaccharide

BACKGROUND: Pro-coagulant membrane microvesicles (MV) derived from platelets and leukocytes are shed into the circulation following receptor-mediated activation, cell-cell interaction, and apoptosis. Platelets are sentinel markers of toll-like receptor 4 (TLR4) activation. Experiments were designed to evaluate the time course and mechanism of direct interactions between platelets and leukocytes following acute activation of TLR4 by bacterial lipopolysaccharide (LPS). METHODOLOGY/PRINCIPAL FINDINGS: Blood from age-matched male and female wild type (WT) and TLR4 gene deleted (dTLR4) mice was incubated with ultra-pure E. coli LPS (500 ng/ml) for up to one hour. At designated periods, leukocyte antigen positive platelets, platelet antigen positive leukocytes and cell-derived MV were quantified by flow cytometry. Numbers of platelet- or leukocyte-derived MV did not increase within one hour following in vitro exposure of blood to LPS. However, with LPS stimulation numbers of platelets staining positive for both platelet- and leukocyte-specific antigens increased in blood derived from WT but not dTLR4 mice. This effect was blocked by inhibition of TLR4 signaling mediated by My88 and TRIF. Seven days after a single intravenous injection of LPS (500 ng/mouse or 20 ng/gm body wt) to WT mice, none of the platelets stained for leukocyte antigen. However, granulocytes, monocytes and apoptotic bodies stained positive for platelet antigens. CONCLUSIONS/SIGNIFICANCE: Within one hour of exposure to LPS, leukocytes exchange surface antigens with platelets through TLR4 activation. In vivo, leukocyte expression of platelet antigen is retained after a single exposure to LPS following turn over of the platelet pool. Acute expression of leukocyte antigen on platelets within one hour of exposure to LPS and the sustained expression of platelet antigen on leukocytes following a single acute exposure to LPS in vivo explains, in part, associations of platelets and leukocytes in response to bacterial infection and changes in thrombotic propensity of the blood