Molecular detection of sugarcane striate virus and sugarcane white streak virus and their prevalence in the Miami World Collection of sugarcane and related grasses

Viruses in the genus Mastrevirus (family Geminiviridae), including those infecting sugarcane, have natural geographical ranges almost exclusively restricted to Africa and the Indian Ocean islands off the African coast. Only sugarcane white streak virus (SWSV) in Barbados and sugarcane striate virus (SStrV) in Florida and Guadeloupe are known to infect a few sugarcane varieties in the Western Hemisphere. In this study, PCR assays were developed to detect these two viruses in sugarcane. Five hundred and seventy-one DNA samples from Saccharum species and interspecific hybrids from the Miami World Collection of sugarcane and related grasses were tested for the presence of SStrV and SWSV by PCR. No variety was found infected by SWSV but SStrV was detected in 19 varieties. PCR data were confirmed by sequencing amplified fragments (248 bp). These fragments shared 93%–100% nucleotide identity with SStrV sequences from the GenBank database. SStrV isolates were distributed in six phylogenetic groups, including the four strains of the virus. Most varieties infected by SStrV originated from Asia, thus confirming a previous hypothesis stating that this virus originated from this continent. Absence of SStrV in commercial sugarcane in Florida also suggested that this virus has not been spread in this location, while infected plants have been present for several decades.     

Drivers of fine-scale avian functional diversity with changing land use: an assessment of the effects of eco-estate housing development and management

Landscape Ecology - The effects of changing land use, and especially urbanisation, on species and functional diversity are of global concern. Eco-estates are a form of urban housing development...     

Ripening reduces the shrinkage of processed dredged material

Purpose

The utilization of dredged material in dike construction as a substitute for traditionally used materials is considered as an option to preserve natural resources such as marsh sediments. As a prerequisite for this application, the equivalency with respect to soil physical and mechanical properties of the materials must be assessed. Previous investigations have shown pronounced differences in shrinkage behavior and desiccation cracking between sediments and dredged material. The key objective of the study was to assess whether shrinkage of processed dredged material can be reduced by further processing, i.e., dewatering, which can be referred to as ripening.

Materials and methods

To compare the shrinkage behavior of the materials, three different methods of different scales were applied. Small-scale methods conducted were the standard procedure for the determination of the shrinkage limit and the determination of the coefficient of linear extensibility (COLE_rod). Large-scale shrink-swell experiments were carried out in a specially constructed test system with 90 l capacity for a period of up to 385 days. Here the materials were ripened, i.e., air-dried, until shrinkage almost ceased, and a rewetting-air-drying cycle was conducted. Shrinkage and swelling were determined during the processes by measuring the changes in volume. On the ripened materials, COLE_rod was determined.

Results and discussion

The experiments show that the shrinkage behavior of processed dredged material can be ameliorated by ripening. COLE_rod of the ripened materials were about 20–80% lower than COLE_rod of the un-ripened materials. The large-scale shrink-swell experiments showed that shrinkage in the second drying cycle amounted to less volume than in the first drying cycle and that shrinkage behavior in contrast to the first drying cycle, where pronounced proportional shrinkage was observed, was dominated by structural and residual shrinkage in this cycle.

Conclusions

Ripening of processed dredged material is considered a useful pre-treatment option to ameliorate the shrink-swell behavior of processed dredged material and to obtain a better functional equivalency with traditionally used dike construction materials such as fine-grained marsh sediments.

     

Role of basidiomycete fungi in the grapevine trunk disease esca

Phaeomoniella chlamydospora and wood-rotting basidiomycete fungi, namely Fomitiporia spp., are known esca pathogens. However, the effect of their mixed infections and the sequence of infection on disease development is unclear. To determine the effects of single and co-inoculations on symptoms, potted Vitis vinifera ‘Crimson Seedless’ was inoculated with P. chlamydospora either alone or in combination with one of four basidiomycetes: Coprinellus radians, Fomitiporia langloisii, F. polymorpha and the novel species Tropicoporus texanus. Basidiomycetes were isolated from vines with foliar symptoms of esca in California and Texas. In sequential co-inoculations, the effects of different sequences of infection (P. chlamydospora first, basidiomycete 6 months later; and vice versa) were tested, compared to simultaneous co-inoculations. Plants inoculated with P. chlamydospora either alone or in combination with a basidiomycete (in any sequence) did not differ significantly in the length of black-streaking lesions. In plants inoculated only with a basidiomycete, the appearance of large brown lesions, coupled with the absence of this wood symptom from control plants, suggests that C. radians, F. langloisii and T. texanus are pathogenic. Foliar symptoms resembling those of esca in the field (marginal and/or interveinal scorching, combined with red and/or yellow discoloration) were statistically more frequent among plants inoculated with F. polymorpha or T. texanus, either simultaneously or following P. chlamydospora, compared to single inoculations. Sequential co-inoculations of a basidiomycete before or after P. chlamydospora were associated with similar lesion lengths, suggesting that basidiomycetes may not require infection by P. chlamydospora in order to extensively colonize the wood.     

Using genetic methods for analysis of fish meals and feeds employed in Greek mariculture

Large quantities of high protein fish meals are needed to sustain cultured species and thus the impact to marine ecosystem has been highly discussed. The aim of this study was to apply a PCR‐cloning methodology for a robust insight into the composition of commercial fish meals and feeds for farmed species of the Greek mariculture, assessing the risk posed by aquaculture to marine ecosystems but also the risk posed by commercial fish feeds to the increase in trophic level of species farmed in Greece. 89% of the sequences were identified to species level and only 11% to genus/family level. Overall, a total of 49 taxa were identified (44 fish species/taxon, five non‐fish species/taxon). Even though small pelagic fish like Engraulis sp. were the main portion, a wide range of species constituted the fish meals and feeds. Plant and animal species were also detected as an alternative protein source. Feed products employed in Greek mariculture still contain large portions of fish meals which increase the mean trophic level of farmed species causing a farming up trend. The results emphasize that such molecular methodologies are needed to certify aquafeeds allowing fish feed producers to demonstrate their commitment to sustainable aquaculture.     

Regional differences in aspen (Populus tremuloides Michx.) seedling response to an established nursery protocol

New Forests - In seedling-based reforestation operations, seed source is known to be an influential variable affecting outplanting success. Adaptive variation among seed sources may also be an...     

Ultrastructural analysis of sequential cyprinid herpesvirus 3 morphogenesis in vitro

Cyprinid herpesvirus 3 (CyHV‐3) is an alloherpesvirus, and it is the aetiological agent of koi herpesvirus disease. Although the complex morphogenic stages of the replication cycle of CyHV‐3 were shown to resemble that of other members of the Herpesvirales, detailed analysis of the sequence and timing of these events was not definitively determined. This study describes these features through a time course using cyprinid cell cultures (KF‐1 and CCB) infected with CyHV‐3 (KHV isolate, H361) and analysed by transmission electron microscopy. Rapid viral entry was noted, with high levels of intracellular virus within 1–4 h post‐infection (hpi). Intranuclear capsid assembly, paracrystalline array formation and primary envelopment of capsids occurred within 4 hpi. Between 1 and 3 days post‐infection (dpi), intracytoplasmic secondary envelopment occurred, as well as budding of infectious virions at the plasma membrane. At 5–7 dpi, the cytoplasm contained cytopathic vacuoles, enveloped virions within vesicles, and abundant non‐enveloped capsids; also there was frequent nuclear deformation. Several morphological features are suggestive of inefficient viral assembly, with production of non‐infectious particles, particularly in KF‐1 cells. The timing of this alloherpesvirus morphogenesis is similar to other members of the Herpesvirales, but there may be possible implications of using different cell lines for CyHV‐3 propagation.     

Examining horizontal and vertical social ties to achieve social–ecological fit in an emerging marine reserve network

1. Most MPA networks are designed only with ecological processes in mind to increase their conservation utility. However, since MPA networks often involve large geographic areas, they also affect and involve multiple actors, institutions, and policy sectors.
2. A key challenge when establishing an effective MPA network is to align the ‘social system’ with the biophysical MPA network (the ‘ecological system’). This challenge is often denoted as ‘social–ecological fit’.
3. Facilitating collaborative social interactions among various actors and stakeholders (social connectivity) is equally as important as accomplishing ecological connectivity. New analytical approaches are required to effectively examine this ‘social’ dimension of fit.
4. An emerging marine reserve network in Jamaica and the recent invasion of Indo‐Pacific lionfish are used as a case study to: (1) examine the extent to which horizontal and vertical social ties bring local and national actors together to collaborate, coordinate, and share knowledge; and (2) assess the extent to which different attributes and features of such multilevel social networks may enhance or inhibit particular aspects of social–ecological fit.
5. Findings suggest that multilevel linkages have played the greatest role in relation to enhancing fit in the marine reserve network in the context of the recent lionfish invasion. However, the long‐term propensity of the multi‐actor and multilevel networks to enhance social–ecological fit is uncertain given the prevalence of weak social ties, lack of a culture of information sharing and collaboration, and limited financial resources.

     

High fluid shear strain causes injury in silver shark: Preliminary implications for Mekong hydropower turbine design

The Lower Mekong Basin is facing unprecedented threats to fish diversity from hydropower development. There is increasing pressure on developers and construction authorities to design solutions to improve fish survival through turbines, thus protecting the resources in regions being developed for hydropower. A hydraulic characteristic of hydropower turbines with known fisheries impacts is fluid shear stress. Elevated shear stress occurs where rapidly flowing water passes near spillways, screens and within turbine draft tubes. Shear stress can have adverse impacts on fish, but no work has assessed whether this holds true for Mekong River species. A flume was used to determine critical tolerances of silver shark, Balantiocheilos melanopterus (Bleeker), to shear stress rates at a high‐velocity jet which simulated a hydropower turbine. Fish were assessed for injury or mortality following exposure. Results were compared against a no‐shear control. Injury and mortality were greater at higher shear stress exposures. Injuries occurred at all shear exposure levels with mortality at shear levels higher than 600/s. This approach should help design future hydropower turbines if data on other species demonstrate similar results. If the likelihood of adverse impact is high, then shear stress will need to be considered in the design of future hydropower facilities.