A scanning electron microscope study of cell wall degradation in elm wood by aggressive and non-aggressive isolates of Ophiostoma ulmi

Degradation of cell walls in elm wood tissue (Ulmus americand) by aggressive and non-aggressive isolates of Ophiostoma ulmi was studied by scanning electron microscopy. Xylem vessel walls were much more affected after infection with the aggressive isolate than after infection with the non-aggressive one.     

Biological control of damping-off caused byPythium ultimum andRhizoctonia solani usingTrichoderma spp. applied as industrial film coatings on seeds

Conidia of sevenTrichoderma strains were applied on cucumber or radish seeds as a simple methyl cellulose coating or through an industrial film coating process. The seeds were sown in a peat-based soil artificially infested byR. solani orP. ultimum. Four strains controlled damping-off caused byR. solani when applied as a simple coating or as an industrial film-coating. Also, four strains significantly reduced damping-off caused byP. ultimum in cucumber. A correlation was found between production of volatile antibiotics in vitro and control ofP. ultimum. Survival during storage varied according to the strain. Better survival was observed for two strains, with a decrease in conidial viability of one order of magnitude after storage for three and five months at 15 ° C and 4 ° C, respectively. The results show the feasibility of biocontrol of seedling diseases by some antagonists applied onto seeds through an industrial film-coating process.     

Population viability and perturbation analyses to support recovery of imperilled Eastern Sand Darter (Ammocrypta pellucida)

Small‐bodied freshwater fishes are often understudied, with the result that data gaps create uncertainties that can complicate and constrain conservation strategies aimed at species recovery. Use of matrix models and perturbation population viability analyses (PVA) are ideally suited for use in studying the consequences of life‐history parameter variation and environmental stochasticity to better understand the fate of threatened small‐bodied fishes. We use data for Eastern Sand Darter (Ammocrypta pellucida) populations from the Thames River, Canada, to explore the consequences of life‐history uncertainties such as age at maturation, multiple clutch sizes and age‐specific fertility for population recovery in this species. Environmental stochasticity acting on all life‐history parameters was found to pose significant risks for the continued viability of lower Thames River populations, with significant chances of local extinction predicted under current conditions. The intrinsic rate of population increase was most sensitive to 0+ survival rates, clutch size and clutch number. As demonstrated here, population models can successfully provide a means of exploring the population dynamics of small‐bodied fishes and can inform managers of risks posed by factors acting on life‐history parameters to affect continued population viability. Management actions for Eastern Sand Darter should focus on strategies designed to ensure successful spawning and improvement of 0+ survival rates, through programmes aimed at the protection, enhancement or recovery of additional spawning and juvenile rearing habitats.     

Global phylogeography of the smooth hammerhead shark: Glacial refugia and historical migration patterns

1. Extreme climate changes during the Cenozoic Era strengthened different biogeographical barriers that decreased the connectivity among populations, triggering lineage diversification of different species worldwide.
2. The mitochondrial DNA control region was employed to explore the phylogeography of Sphyrna zygaena, a globally distributed species threatened by unsustainable, illegal, unreported and unregulated fisheries triggered by the international shark fin trade. It is listed as ‘Vulnerable’ by the IUCN Red List and its trade is regulated by CITES Appendix II.
3. Only 13 haplotypes were found with low genetic diversity levels (hd = 0.686 ± 0.014; π = 0.00206 ± 0.00004) compared with other species of the Sphyrnidae family. The species has a very strong phylogeographic population structure among the Atlantic, Indian and Pacific Oceans (Φ_ST = 0.79132). Worldwide, there are six distinct populations with some haplotype sharing.
4. These populations are probably connected by a stepping-stone dispersal of a small number of migrants per generation from the Indo-Pacific towards the Atlantic. Modelling suggests that S. zygaena diverged into two lineages around 6.96 million years ago which have been isolated in glacial refuges in the Atlantic and Indo-Pacific oceans; and after deglaciation, a population expansion probably permitted secondary contact.
5. Conservation plans to establish differentiated management units should be adopted in each of the identified populations. Among these, the Eastern Central Atlantic and West Indo-Pacific are the most important areas for the species considering the historical migration routes that act as a bridge connecting the Atlantic and Indo-Pacific Oceans while the Gulf of Guinea connects the Atlantic populations. Still, further studies are required to know if these populations are also linked with nursery areas for the species.
6. The results herein can help to delimit the main evolutionarily significant units to implement effective policies to establish differentiated management units as starting points to genetic monitoring programmes for Sphyrna zygaena.

     

Commercial sex workers: Victims,vectors or fighters of the HIV epidemic in Cambodia?

Abstract: This paper looks at the knowledge, attitudes and behaviour of commercial sex workers (CSWs) in Cambodia regarding HIV/AIDS and condom use. The findings are based on semistructured interviews and focus groups with brothel‐based and self‐employed CSWs, and interviews with people who work with them. The respondents live in two towns near the Thai border served by Medecins Sans Frontiers sexually transmitted disease clinics set up to reduce the transmission of HIV. Most CSWs had attended the clinics. Knowledge of HIV and the ability of condoms to prevent infection was universal. The desire to use condoms with clients was also universal. Most CSWs were active and skilful in negotiating condom use with clients. However, many CSWs who wanted to use condoms failed to do so on occasion due to disparate power relationship with brothel owners and clients, and economic desperation. In addition, some exempted regular or special clients from condom use due to emotional isolation and misconceptions over susceptibility to HIV. The current 100% Condom Use Policy in place in Cambodia is not compatible with voluntary programmes such as the successful Medecins Sans Frontiers clinics. The government policy also fails to address the broader social and economic factors that make CSWs unable to enforce condom use when a client does not desire to do so.