Synaptic input to dentate granule cell basal dendrites in a rat model of temporal lobe epilepsy.

In patients with temporal lobe epilepsy some dentate granule cells develop basal dendrites. The extent of excitatory synaptic input to basal dendrites is unclear, nor is it known whether basal dendrites receive inhibitory synapses. We used biocytin to intracellularly label individual granule cells with basal dendrites in epileptic pilocarpine-treated rats. An average basal dendrite had 3.9 branches, was 612 microm long, and accounted for 16% of a cell's total dendritic length. In vivo intracellular labeling and postembedding GABA-immunocytochemistry were used to evaluate synapses with basal dendrites reconstructed from serial electron micrographs. An average of 7% of 1,802 putative synapses were formed by GABA-positive axon terminals, indicating synaptogenesis by interneurons. Ninety-three percent of the identified synapses were GABA-negative. Most GABA-negative synapses were with spines, but at least 10% were with dendritic shafts. Multiplying basal dendrite length/cell and synapse density yielded an estimate of 180 inhibitory and 2,140 excitatory synapses per granule cell basal dendrite. Based on previous estimates of synaptic input to granule cells in control rats, these findings suggest an average basal dendrite receives approximately 14% of the total inhibitory and 19% of excitatory synapses of a cell. These findings reveal that basal dendrites are a novel source of inhibitory input, but they primarily receive excitatory synapses

Principles Underpinning Best Practice Management of the Damage Due to Pests in Australia

Principles contained in the 1993 publication “Managing Vertebrate Pests: Principles & Strategies” were developed during a review of past and current pest management practices. They were used to guide the development of a series of management guidelines for our major vertebrate pests – feral pigs, house mice, European rabbits, red fox, feral pigs, feral horses, wild dogs, and carp. The principles have been constantly refined through subsequent on ground experience in working with stakeholders to implement best practice management programs for pest animals. In this paper, we present what we now consider the seven principles that underpin best practice management of pest animals. They are: 1. A pest is human construct. 2. All key stakeholders need to be actively engaged and consulted. 3. Rarely can pests be eradicated. 4. Most pest management needs to focus on the outcome, reduction in damage, not just killing pests. 5. A whole-system approach is required for managing pest damage. 6. Most pest management occurs in ecosystems in which our knowledge is imperfect. 7. An effective monitoring and evaluation strategy is essential for all management interventions. Together, the principles comprise the strategic approach to pest management. We explain the rationale behind these principles and illustrate them with examples

Assessment of non-target risks from sodium fluoroacetate (1080), para-aminopropiophenone (PAPP) and sodium cyanide (NaCN) for fox-incursion response in Tasmania

Context Access to effective toxicants and delivery systems that target red foxes (Vulpes vulpes) are likely to be required as part of a management strategy in the event of future red fox incursions into Tasmania. Potential toxicants include sodium fluoroacetate (1080), para-aminopropiophenone (PAPP) and sodium cyanide (NaCN). Aims To assess the risk of three toxicants (1080, PAPP and NaCN) to non-target native Tasmanian mammals and birds and domestic dogs and cats. Methods We identified native Tasmanian mammal and bird species that may potentially consume fox baits, by reviewing the ecological traits of native species and by monitoring 180 buried bait stations with video cameras. We also assess the potential risk to non-target species of dying from a single standard dose of each of the three toxicants. Key results Seven native mammal and 20 native bird species have the potential to consume fox bait. All vertebrates would be susceptible to a single dose of NaCN. Consumption of a single fox bait containing 3mg 1080 may be lethal to five native mammals, three native birds, and the domestic cat (Felis catus) and dog (Canis familiaris). Consumption of a single fox bait containing 226mg PAPP may be lethal to the spotted-tailed quoll (Dasyurus maculatus) and the domestic cat and dog. Delivery of toxicants via a mechanical ejector would reduce non-target exposure to toxicants. Conclusions It appears that PAPP would provide a useful alternative to 1080 for use in lethal fox control in Tasmania, either in the event of an incursion or in the eradication of an established population. NaCN is not suitable for broadscale use in Tasmania because of the high susceptibility of all vertebrates to this toxicant. Nevertheless, NaCN would be useful in highly restricted areas in the event of an incursion where carcass recovery is important. The use of a mechanical ejector to target delivery of toxicants to red foxes would reduce non-target risks. Implications Our results clarify theoretical non-target risks from any future fox-poisoning programs in Tasmania and highlight the need for further research on the susceptibility of native species to PAPP as a potential alternative to 1080