Land masses and oceanic currents drive population structure of Heritiera littoralis,a widespread mangrove in the Indo‐West Pacific

Phylogeographic forces driving evolution of sea‐dispersed plants are often influenced by regional and species characteristics, although not yet deciphered at a large spatial scale for many taxa like the mangrove species Heritiera littoralis. This study aimed to assess geographic distribution of genetic variation of this widespread mangrove in the Indo‐West Pacific region and identify the phylogeographic factors influencing its present‐day distribution. Analysis of five chloroplast DNA fragments’ sequences from 37 populations revealed low genetic diversity at the population level and strong genetic structure of H. littoralis in this region. The estimated divergence times between the major genetic lineages indicated that glacial level changes during the Pleistocene epoch induced strong genetic differentiation across the Indian and Pacific Oceans. In comparison to the strong genetic break imposed by the Sunda Shelf toward splitting the lineages of the Indian and Pacific Oceans, the genetic differentiation between Indo‐Malesia and Australasia was not so prominent. Long‐distance dispersal ability of H. littoralis propagules helped the species to attain transoceanic distribution not only across South East Asia and Australia, but also across the Indian Ocean to East Africa. However, oceanic circulation pattern in the South China Sea was found to act as a barrier creating further intraoceanic genetic differentiation. Overall, phylogeographic analysis in this study revealed that glacial vicariance had profound influence on population differentiation in H. littoralis and caused low genetic diversity except for the refugia populations near the equator which might have persisted through glacial maxima. With increasing loss of suitable habitats due to anthropogenic activities, these findings therefore emphasize the urgent need for conservation actions for all populations throughout the distribution range of H. littoralis.     

Predicting the distributions of predator (snow leopard) and prey (blue sheep) under climate change in the Himalaya

Future climate change is likely to affect distributions of species, disrupt biotic interactions, and cause spatial incongruity of predator–prey habitats. Understanding the impacts of future climate change on species distribution will help in the formulation of conservation policies to reduce the risks of future biodiversity losses. Using a species distribution modeling approach by MaxEnt, we modeled current and future distributions of snow leopard (Panthera uncia) and its common prey, blue sheep (Pseudois nayaur), and observed the changes in niche overlap in the Nepal Himalaya. Annual mean temperature is the major climatic factor responsible for the snow leopard and blue sheep distributions in the energy‐deficient environments of high altitudes. Currently, about 15.32% and 15.93% area of the Nepal Himalaya are suitable for snow leopard and blue sheep habitats, respectively. The bioclimatic models show that the current suitable habitats of both snow leopard and blue sheep will be reduced under future climate change. The predicted suitable habitat of the snow leopard is decreased when blue sheep habitats is incorporated in the model. Our climate‐only model shows that only 11.64% (17,190 km²) area of Nepal is suitable for the snow leopard under current climate and the suitable habitat reduces to 5,435 km² (reduced by 24.02%) after incorporating the predicted distribution of blue sheep. The predicted distribution of snow leopard reduces by 14.57% in 2030 and by 21.57% in 2050 when the predicted distribution of blue sheep is included as compared to 1.98% reduction in 2030 and 3.80% reduction in 2050 based on the climate‐only model. It is predicted that future climate may alter the predator–prey spatial interaction inducing a lower degree of overlap and a higher degree of mismatch between snow leopard and blue sheep niches. This suggests increased energetic costs of finding preferred prey for snow leopards – a species already facing energetic constraints due to the limited dietary resources in its alpine habitat. Our findings provide valuable information for extension of protected areas in future.     

Screening of metal uptake by plant colonizers growing on abandoned copper mine in Kapunda,South Australia

Systematic site survey for sample collection and analysis was conducted at a derelict copper (Cu) mine at Kapunda, South Australia. Cu concentrations in the soils at this former mine ranged from 65–10107 mg kg^?1. The pH and EC varied widely in the 3.9–8.4 and 152–7311 µS ranges, respectively. Nine plant species growing over the copper mine site were selected to screen for metal uptake to determine their suitability for phytoremediation. The Australian native tree species Eucalyptus camaldulensis indicated enrichment factor (EF) of 2.17, 1.89, and 1.30 for Cu, Zn, and Pb, respectively, suggesting that this species of tree can accumulate these metals to some degree. The stress-resistant exotic olive, Olea europaea exhibited EF of ≤ 0.01 for Cu, Cd, and Pb, and 0.29 for Zn, which is characteristic of an excluder plant. Acacia pycnantha, the Australian pioneer legume species with EF 0.03, 0.80, 0.32, and 0.01 for Cu, Zn, Cd, and Pb, respectively, emerged as another strong metal excluder and consequently as an ideal metal stabilizer.     

Suitability of tomato leaves for larval development of Potato Tuber Moth,Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae)

The potato tuber moth (PTM) is an important pest of the potato plant and its tuber. With the expansion of its geographic range, the PTM could be potential threat to the tomato (Solanum lycopersicum L.), a congeneric species of the potato. To assess that risk, we tested larval feeding and development of PTM on leaves of five cultivated tomato varieties namely Moneymaker, Campari, Ailsa Craig, LA3475, E6203 and one wild tomato variety S. pimpinellifolium. PTM larvae accepted all tested plant leaves and developed into adults. Larval development was fastest on the Ailsa Craig variety. Pupae developed fastest on the Moneymaker variety and slowest on LA3475. Host acceptance and survival were highest on Ailsa Craig and lowest on LA3475. The significantly highest male proportion occurred on LA3475 variety. The study showed that PTM could be a potential threat to tomato cultivation which is rapidly increasing in temperate regions owing to climate change.     

Dual emission carbon dots from carotenoids: Converting a single emission to dual emission

Dual emission carbon dots have a high potential for use as fluorescence‐based sensors with higher selectivity and sensitivity. This study demonstrated the possibility of conversion of a biological molecular system with a single emission peak to a double emission carbon dots system. This report is the first to describe the synthesis of dual emission carbon dots by tuning the electronic environment of a conjugated system. Here we prepared carbon dots from a natural extract, from which carotenoids were used as a new source for carbon dots. Formation of the carbon dots was confirmed by images obtained under a transmission electron microscope as well as from a dynamic light scattering study. The prepared carbon dots system was characterized and its optical property was monitored. The study showed that, after irradiation with microwaves, the fluorescence intensity of the whole system changed, without any change in the original peak position of the carotenoid but with the appearance of an additional peak. A Fourier transform infrared study confirmed breaking of the conjugated system. When using ethylene glycol as a surface passivating agent added to these carotenoid carbon dots, the dual emission spectra became more distinct.     

Deciphering the global phylogeography of a coastal shrub (Scaevola taccada) reveals the influence of multiple forces on contemporary population structure

The phylogeography of coastal plant species is heavily influenced by past sealevel fluctuations, dispersal barriers, and life-history traits, such as long-distance dispersal ability of the propagules. Unlike the widely studied mangroves, phylogeographic patterns have remained mostly obscure for other coastal plant species. In this study, we sampled 42 populations of Scaevola taccada (Gaertn.) Roxb., a coastal shrub of the family Goodeniaceae, from 17 countries across its distribution range. We used five chloroplast DNA (cpDNA) and 14 nuclear microsatellite (simple sequence repeat [SSR]) markers to assess the influence of abiotic factors and population genetic processes on the phylogeographic pattern of the species. Geographical distribution of cpDNA haplotypes suggests that the species originated in Australia, followed by historical dispersal and expansion of its geographic range. Multiple abiotic factors, including the sealevel changes during the Pleistocene, the presence of landmasses like the Malay Peninsula, and contemporary oceanic circulation patterns, restricted gene flow between geographically distinct populations, thereby creating low haplotype diversity and a strong population structure. Population genetic processes acted on these isolated populations, leading to high nuclear genetic diversity and population differentiation, as revealed from analyzing the polymorphic SSR loci. Although genetic divergence was mostly concordant between cpDNA and SSR data, asymmetrical gene flow and ancestral polymorphism could explain the discordance in the detailed genetic structure. Overall, our findings indicate that abiotic factors and population genetic processes interactively influenced the evolutionary history and current phylogeographic pattern of S. taccada across its distribution range.     

RhoA and Rac1 are both required for efficient wound closure of airway epithelial cells

Repair of the airway epithelium after injury is critical for restoring normal lung. The reepithelialization process involves spreading and migration followed later by cell proliferation. Rho-GTPases are key components of the wound healing process in many different types of tissues, but the specific roles for RhoA and Rac1 vary and have not been identified in lung epithelial cells. We investigated whether RhoA and Rac1 regulate wound closure of bronchial epithelial cells. RhoA and Rac1 proteins were efficiently expressed in a cell line of human bronchial epithelial cells (16HBE) by adenovirus-based gene transfer. We found that both constitutively active RhoA and dominant negative RhoA inhibited wound healing, suggesting that both activation and inhibition of RhoA interfere with normal wound healing. Overexpression of wild-type Rac1 induced upregulation of RhoA, disrupted intercellular junctions, and inhibited wound closure. Dominant negative Rac1 also inhibited wound closure. Inhibition of the downstream effector of RhoA, Rho-kinase, with Y-27632 suppressed actin stress fibers and focal adhesion formation, increased Rac1 activity, and stimulated wound closure. The activity of both RhoA and Rac1 are influenced by the polymerization state of microtubules, and cell migration involves coordinated action of actin and microtubules. Microtubule depolymerization upon nocodazole treatment led to an increase in focal adhesions and decreased wound closure. We conclude that coordination of both RhoA and Rac1 activity contributes to bronchial epithelial wound repair mechanisms in vitro, that inhibition of Rho-kinase accelerates wound closure, and that efficient repair involves intact microtubules.