A visual method for indexing muskrat populations

The native range for muskrats (Ondatru zibethicus) includes much of North America, but they also have been introduced beyond their native range, including into the Fall River, California, where they have come into conflict with human interests. An easily applied method to assess their abundance is an important need for their management. We developed a muskrat visual index (MVI) to provide the information necessary to address this need. Observations were made at randomly located sites along the river. The number of muskrats observed during a 45 min period was recorded during the late afternoon peak activity time at each site on multiple days. The mean number observed over sites was calculated for each day. The index was the mean of the daily means. These design and measurement methods present valuable advantages over most traditional muskrat indexing methods in this environment. Traditional methods usually involve counting burrows or houses. However, in a relatively stable environment such as along the Fall River, muskrat burrows and houses tend to be long-lasting structures, making acute changes in population difficult to detect by there methods. Examining these structures for activity can be time-consuming and labor-intensive. Of particular importance, the statistical properties inherent to the MVI data structure permit calculation of standard errors, confidence intervals and statistical tests allowing quantitative comparisons among MVI values. Development of a management program for muskrats on the Fall River will require understanding of muskrat population fluctuations and densities, as well as knowledge of the effectiveness (short- and long-term) of control strategies. Here we develop a useful method, derive its statistical properties, and present baseline information for managing muskrats along the Fall River

A visual method for indexing muskrat populations

The native range for muskrats (Ondatru zibethicus) includes much of North America, but they also have been introduced beyond their native range, including into the Fall River, California, where they have come into conflict with human interests. An easily applied method to assess their abundance is an important need for their management. We developed a muskrat visual index (MVI) to provide the information necessary to address this need. Observations were made at randomly located sites along the river. The number of muskrats observed during a 45 min period was recorded during the late afternoon peak activity time at each site on multiple days. The mean number observed over sites was calculated for each day. The index was the mean of the daily means. These design and measurement methods present valuable advantages over most traditional muskrat indexing methods in this environment. Traditional methods usually involve counting burrows or houses. However, in a relatively stable environment such as along the Fall River, muskrat burrows and houses tend to be long-lasting structures, making acute changes in population difficult to detect by there methods. Examining these structures for activity can be time-consuming and labor-intensive. Of particular importance, the statistical properties inherent to the MVI data structure permit calculation of standard errors, confidence intervals and statistical tests allowing quantitative comparisons among MVI values. Development of a management program for muskrats on the Fall River will require understanding of muskrat population fluctuations and densities, as well as knowledge of the effectiveness (short- and long-term) of control strategies. Here we develop a useful method, derive its statistical properties, and present baseline information for managing muskrats along the Fall River

Enhancing Science Impact in the Coastal Zone through Adaptive Learning

The impact of science to support coastal management may be reduced through social and institutional barriers. Some of these barriers include ineffective community engagement, lack of interaction between scientists and decision makers, and institutional decision-making tradition related to hierarchical mandates. A three-year project has commenced to examine the role of adaptive learning in overcoming some of these barriers to maximize pathways for science and improve decisions made in the coastal zone. Adaptive learning is one of five project areas targeted to enhance science impact, being undertaken by a consortium of nine Australian universities funded through the CSIRO Collaboration Fund. Two of the strategies being explored to maximize adaptive learning to improve science impact include: (i) development of an on-line toolkit for embedding adaptive learning within coastal organizations; and (ii) development and testing of monitoring and evaluation frameworks to improve adaptive learning interventions. While focused on an Australian context, the project addresses broad issues of social and institutional barriers that have relevance for many coastal scientists and decision makers around the globe

Sequence Variants of the Phytophthora sojae RXLR Effector Avr3a/5 Are Differentially Recognized by Rps3a and Rps5 in Soybean

The perception of Phytophthora sojae avirulence (Avr) gene products by corresponding soybean resistance (Rps) gene products causes effector triggered immunity. Past studies have shown that the Avr3a and Avr5 genes of P. sojae are genetically linked, and the Avr3a gene encoding a secreted RXLR effector protein was recently identified. We now provide evidence that Avr3a and Avr5 are allelic. Genetic mapping data from F2 progeny indicates that Avr3a and Avr5 co-segregate, and haplotype analysis of P. sojae strain collections reveal sequence and transcriptional polymorphisms that are consistent with a single genetic locus encoding Avr3a/5. Transformation of P. sojae and transient expression in soybean were performed to test how Avr3a/5 alleles interact with soybean Rps3a and Rps5. Over-expression of Avr3a/5 in a P. sojae strain that is normally virulent on Rps3a and Rps5 results in avirulence to Rps3a and Rps5; whereas silencing of Avr3a/5 causes gain of virulence in a P. sojae strain that is normally avirulent on Rps3a and Rps5 soybean lines. Transient expression and co-bombardment with a reporter gene confirms that Avr3a/5 triggers cell death in Rps5 soybean leaves in an appropriate allele-specific manner. Sequence analysis of the Avr3a/5 gene identifies crucial residues in the effector domain that distinguish recognition by Rps3a and Rps5

Infection of Rrs1 barley by an incompatible race of the fungus Rhynchosporium secalis expressing the green fluorescent protein

Scald disease of barley, caused by the fungal pathogen Rhynchosporium secalis, is one of the most serious diseases of this crop worldwide. Disease control is achieved in part by deployment of major resistance (Rrs) genes in barley. However, in both susceptible and resistant barley plants, R. secalis is able to complete a symptomless infection cycle. To examine the R. secalis infection cycle, Agrobacterium tumefaciens-mediated transformation was used to generate R. secalis isolates expressing the green fluorescent protein or DsRed fluorescent protein, and that were virulent on an Rrs2 plant (cv. Atlas), but avirulent on an Rrs1 plant (cv. Atlas 46). Confocal laser scanning microscopy revealed that R. secalis infected the susceptible cultivar and formed an extensive hyphal network that followed the anticlinal cell walls of epidermal cells. In the resistant cultivar, hyphal development was more restricted and random in direction of growth. In contrast to earlier models of R. secalis infection, epidermal collapse was not observed until approximately 10 days post-inoculation in both cultivars. Sporulation of R. secalis was observed in both susceptible and resistant interactions. Observations made using the GFP-expressing isolate were complemented and confirmed using a combination of the fluorescent probes 5-chloromethylfluorescein diacetate and propidium iodide, in the non-transformed wild-type isolate. The findings will enable the different Rrs genes to be better characterized in the effect they exert on pathogen growth and may aid in identification of the most effective resistance

An RxLR effector from phytophthora infestans prevents re-localisation of two plant NAC transcription factors from the endoplasmic reticulum to the nucleus

The plant immune system is activated following the perception of exposed, essential and invariant microbial molecules that are recognised as non-self. A major component of plant immunity is the transcriptional induction of genes involved in a wide array of defence responses. In turn, adapted pathogens deliver effector proteins that act either inside or outside plant cells to manipulate host processes, often through their direct action on plant protein targets. To date, few effectors have been shown to directly manipulate transcriptional regulators of plant defence. Moreover, little is known generally about the modes of action of effectors from filamentous (fungal and oomycete) plant pathogens. We describe an effector, called Pi03192, from the late blight pathogen Phytophthora infestans, which interacts with a pair of host transcription factors at the endoplasmic reticulum (ER) inside plant cells. We show that these transcription factors are released from the ER to enter the nucleus, following pathogen perception, and are important in restricting disease. Pi03192 prevents the plant transcription factors from accumulating in the host nucleus, revealing a novel means of enhancing host susceptibility

Activity patterns of free-ranging koalas (Phascolarctos cinereus) revealed by accelerometry

An understanding of koala activity patterns is important for measuring the behavioral response of this species to environmental change, but to date has been limited by the logistical challenges of traditional field methodologies. We addressed this knowledge gap by using tri-axial accelerometer data loggers attached to VHF radio collars to examine activity patterns of adult male and female koalas in a high-density population at Cape Otway, Victoria, Australia. Data were obtained from 27 adult koalas over two 7-d periods during the breeding season: 12 in the early-breeding season in November 2010, and 15 in the late-breeding season in January 2011. Multiple 15 minute observation blocks on each animal were used for validation of activity patterns determined from the accelerometer data loggers. Accelerometry was effective in distinguishing between inactive (sleeping, resting) and active (grooming, feeding and moving) behaviors. Koalas were more active during the early-breeding season with a higher index of movement (overall dynamic body acceleration [ODBA]) for both males and females. Koalas showed a distinct temporal pattern of behavior, with most activity occurring from mid-afternoon to early morning. Accelerometry has potential for examining fine-scale behavior of a wide range of arboreal and terrestrial species

A molecular insight into algal-oomycete warfare : cDNA analysis of Ectocarpus siliculosus infected with the basal oomycete Eurychasma dicksonii

Peer reviewedPublisher PD