Interactive Effects of Abiotic Stress and Elevated CO2 on Physio-Chemical and Photosynthetic Responses in Suaeda Species

Suaeda fruticosa and S. monoica are important halophytes for ecological rehabilitation of saline lands. We report differential physio-chemical, photosynthetic, and chlorophyll fluorescence responses in these halophytes under 100 mM sodium chloride (NaCl), 50% strength (16.25 ppt) of seawater (SW)-imposed salinity, and 10% polyethylene glycol 6000 imposed osmotic stress at 380 (ambient) and 1200 (elevated) µmol mol^–1 CO₂ concentrations. SW salinity enhanced the growth in both species; however, compared with S. fruticosa, the S. monoica exhibited comparatively better growth and biomass accumulation under saline conditions at elevated CO₂. Results demonstrated better photosynthetic performances of S. monoica under stress conditions at both levels of CO₂, and this resulted in higher accumulation of carbon, nitrogen, sugar, and starch contents. S. monoica exhibited improved antenna size, electron transfer at PSII donor side, and efficient working of photosynthetic machinery at elevated CO₂, which might be due to efficient upstream utilization of reducing power to fix the CO₂. The δ¹³C results supported the operation of C₄ CO₂ fixation in S. monoica and C₃ or intermediate pathway of CO₂ fixation in S. fruticosa. Lower accumulation of reactive oxygen species, reduced membrane damage, lowered solute potential, and higher accumulation of proline and polyphenol contents indicated elevated CO₂-induced abiotic stress tolerance in Suaeda. Higher activity of antioxidant enzymes in both species at both levels of CO₂ help plants to combat the oxidative stress. Upregulation of NADP-dependent malic enzyme and NADP-dependent malate dehydrogenase genes indicated their role in abiotic stress tolerance as well as photosynthetic carbon (C) sequestration. Operation of C₄ type CO₂ fixation in S. monoica and an intermediate CO₂ fixation in S. fruticosa could be the possible reason for the superior photosynthetic efficiency of S. monoica under stress conditions at elevated CO₂.

     

The DNA Replication,Repair, and Recombination Pathway Genes Modulating Yield and Stress Tolerance Traits in Chickpea

DNA replication, repair, and recombination (DRRR) are the fundamental processes required for faithful transmission of genetic information within and between generations. The DRRR genes protect the cells from potential mutations and damage during the developmental phases and stress conditions. Thus, these genes indirectly regulate diverse important agronomic traits in a crop plant. A genome-wide survey of six DRRR pathway genes, namely, DNA replication, Base Excision Repair, Nucleotide Excision Repair, Homologous Recombination, Mismatch Excision Repair, and Non-Homologous End-Joining, identified 157 DRRR genes in chickpea. Phylogenetic analysis of these genes within the legume clades and model plant Arabidopsis identified 42 conserved DRRR genes exhibiting clade-specific evolutionary patterns. Integrating the gene-based association mapping with differential expression profiling identified the natural alleles of the potential DRRR genes, primarily regulating flowering and maturation time and involved in drought tolerance of chickpea. Identifying and understanding DRRR genes’ roles in regulating yield and stress tolerance traits in a vital grain legume like chickpea is requisite for its future crop improvement endeavors. Manipulation of promising functionally relevant DRRR genes will pave the way for simultaneous improvement in multiple beneficial agronomic traits in chickpea.

     

The red seaweed Kappaphycus alvarezii antiporter gene (KaNa+/H+) confers abiotic stress tolerance in transgenic tobacco

Molecular Biology Reports - Plant establishment, growth, development and productivity are adversely affected by abiotic stresses that are dominant characteristics of environmentally...     

Contemporary human‐altered landscapes and oceanic barriers reduce bumble bee gene flow

Much of the world's terrestrial landscapes are being altered by humans in the form of agriculture, urbanization and pastoral systems, with major implications for biodiversity. Bumble bees are one of the most effective pollinators in both natural and cultivated landscapes, but are often the first to be extirpated in human‐altered habitats. Yet, little is known about the role of natural and human‐altered habitats in promoting or limiting bumble bee gene flow. In this study, I closely examine the genetic structure of the yellow‐faced bumble bee, Bombus vosnesenskii, across the southwestern US coast and find strong evidence that natural oceanic barriers, as well as contemporary human‐altered habitats, limit bee gene flow. Heterozygosity and allelic richness were lower in island populations, while private allelic richness was higher in island populations compared to mainland populations. Genetic differentiation, measured for three indices across the 1000 km study region, was significantly greater than the null expectation (F_ST = 0.041, F’_ST = 0.044 and D_est = 0.155) and correlated with geographic distance. Furthermore, genetic differentiation patterns were most strongly correlated with contemporary (2011) not past (2006, 2001) resistance maps calibrated for high dispersal limitation over oceans, impervious habitat and croplands. Despite the incorporation of dramatic elevation gradients, the analyses reveal that oceans and contemporary human land use, not mountains, are the primary dispersal barriers for B. vosnesenskii gene flow. These findings reinforce the importance of maintaining corridors of suitable habitat across the distribution range of native pollinators to promote their persistence and safeguard their ability to provide essential pollination services.     

Intracellular adaptor molecules and AR signalling in the tumour microenvironment

Androgen deprivation therapy is the mainstay for treating advanced prostate cancer. A better understanding in the complexity of the androgen receptor (AR) signalling pathway has highlighted that this form of treatment is not sufficient. Since Huggins and Hodges made their crucial observations on the benefits of castration for prostate cancer, significant progress has been achieved in understanding the importance of the cross-talk between the hormone signalling pathway and the kinase signalling network. We now know that preventing androgen production or ligand binding to the AR does not necessarily mark the end of the road for prostate tumour growth. Emerging evidence suggests that there exists a complex set of compensatory mechanisms which allows growth factors to push the transformed cells into a ‘survival adaptation mode’ within the tumour microenvironment. An increase in autocrine and paracrine cascades of growth factor are the most commonly reported events to correlate with progression of androgen-dependent disease to a disseminated androgen independent state. The mechanism of how growth factors can sustain AR activation when cells are deprived of androgens is unknown. This is due to the lack of information about the critical factors linking the intracellular signalling molecules associated with the downstream AR signalling events triggered by growth factors. The aim of this mini review is to highlight a potentially new insight into how intracellular adaptor molecules activated by growth factors may influence and act as a molecular switch to allow the continuation of AR activity in the presence of therapeutic anti-androgens following chemical or surgical castration.     

Purification and partial characterization of an extracellular alginate lyase from <Emphasis Type="Italic">Aspergillus oryzae</Emphasis> isolated from brown seaweed

The extracellular enzyme alginate lyase produced from marine fungus Aspergillus oryzae isolated from brown alga Dictyota dichotoma was purified, partially characterized, and evaluated for its sodium alginate depolymerization abilities. The enzyme characterization studies have revealed that alginate lyase consisted of two polypeptides with about 45 and 50 kDa each on 10% sodium dodecyl sulfate polyacrylamide gel electrophoresis and showed 140-fold higher activity than crude enzyme under optimized pH (6.5) and temperature (35°C) conditions. Zn²⁺, Mn²⁺, Cu²⁺, Mg²⁺, Co²⁺ and NaCl were found to enhance the enzyme activity while (Ca²⁺, Cd²⁺, Fe²⁺, Hg²⁺, Sr²⁺, Ni²⁺), glutathione, and metal chelators (ethylenediaminetetraacetic acid and ethylene glycol tetraacetic acid) suppressed the activity. Fourier transform infrared and thin-layer chromatography analysis of depolymerized sodium alginate indicated the enzyme specificity for cleaving at the β-1,4 glycosidic bond between polyM and polyG blocks of sodium alginate and therefore resulted in estimation of relatively higher polyM content than polyG. Comparison of chemical shifts in ¹³C nuclear magnetic resonance spectra of both polyM and polyG from that of sodium alginate also showed further evidence for enzymatic depolymerization of sodium alginate.     

CyLoP-1: a novel cysteine-rich cell-penetrating peptide for cytosolic delivery of cargoes

Cell-penetrating peptides (CPPs) may have impli-cations in biomedical sciences by improving the delivery of a wide variety of drugs through the membrane barrier. CPPs are generally taken up by endocytotic pathways, and vesicular encapsulation is a limiting factor in the area of intracellular targeting. A novel, cationic cysteine-rich CPP, CyLoP-1, has been developed exhibiting distinguished diffused cytosolic distribution along with endosomal uptake at low micromolar concentrations. Comparative uptake analysis with known CPPs showed CyLoP-1 as a promising delivery vector to access the cytosol in a variety of cell types. In addition to the positively charged residues, the presence of cysteines and tryptophans proved to be essential to maintain its functionality. Also, the oxidation status of the cysteines played an important role for the uptake efficiency of CyLoP-1, with the disulfide-containing form being more effective. The distinct feature of CyLoP-1 to enter the cytosol was further explored by the covalent attachment of cargoes of different nature and sizes. In particular, induction of caspase-3 activity (indicating apoptosis) by a CyLoP-1-SmacN7 conjugate proved successful delivery of the pro-apoptotic cargo to its site of action in the cytosol. Efficient intracellular delivery into the entire cytosol already at low micromolar concentrations makes CyLoP-1 a promising candidate for cytosolic delivery of cargoes of small sizes. Thus, this peptide might prove to be useful for efficient transmembrane delivery of agents directed to cytosolic targets.