Modeling the eradication of invasive mammals using the sterile male technique

Large vertebrates, like the domestic goat (Capra hircus), have been transported all over the world and are an ecological disaster to numerous island and mainland ecosystems. Eradication measures for such species are generally centered on lethal methods of removing individuals, an increasingly difficult process as populations become smaller and individual animals become much more difficult to detect. In addition, methods of lethal removal are becoming less desirable in the public eye, prompting the necessity to explore alternatives. Here we investigate the use of the sterile males technique as an effective strategy in the eradication of large mammals. The results of our simulations suggest that the use of sterile males as a single strategy would only be an effective measure to eradicate relatively small (no more than 100 individuals) isolated feral vertebrate populations. However, our results indicate that the technique could be employed as a successful and potentially cost-effective end-point complement to lethal control and/or as a preventative measure against re-invasion.     

Abnormal proteins of shortened length are preferentially degraded in the cytosol of cultured MRC5 fibroblasts

Puromycyl peptides were degraded in MRC5 fibroblasts more rapidly than normal proteins labelled for the corresponding length of time for both long and short labelling periods. The degradation of the puromycyl peptides occurred almost exclusively in the cytosol of the cells. Even when the half-lives of normal and puromycyl peptides were manipulated to be similar, proportionally more of the normal proteins were degraded in the lysosomes. The rapid degradation of the puromycyl peptides was not due to the inhibition of protein synthesis brought about by puromycin but was due to the structure of the substrates themselves. The degree and intracellular site of degradation of puromycyl peptides closely mimic those of abnormal (missense) proteins containing amino acid analogues.     

Anhydrobiosis and Freezing-Tolerance: Adaptations That Facilitate the Establishment of Panagrolaimus Nematodes in Polar Habitats

Anhydrobiotic animals can survive the loss of both free and bound water from their cells. While in this state they are also resistant to freezing. This physiology adapts anhydrobiotes to harsh environments and it aids their dispersal. Panagrolaimus davidi, a bacterial feeding anhydrobiotic nematode isolated from Ross Island Antarctica, can survive intracellular ice formation when fully hydrated. A capacity to survive freezing while fully hydrated has also been observed in some other Antarctic nematodes. We experimentally determined the anhydrobiotic and freezing-tolerance phenotypes of 24 Panagrolaimus strains from tropical, temperate, continental and polar habitats and we analysed their phylogenetic relationships. We found that several other Panagrolaimus isolates can also survive freezing when fully hydrated and that tissue extracts from these freezing-tolerant nematodes can inhibit the growth of ice crystals. We show that P. davidi belongs to a clade of anhydrobiotic and freezing-tolerant panagrolaimids containing strains from temperate and continental regions and that P. superbus, an early colonizer at Surtsey island, Iceland after its volcanic formation, is closely related to a species from Pennsylvania, USA. Ancestral state reconstructions show that anhydrobiosis evolved deep in the phylogeny of Panagrolaimus. The early-diverging Panagrolaimus lineages are strongly anhydrobiotic but weakly freezing-tolerant, suggesting that freezing tolerance is most likely a derived trait. The common ancestors of the davidi and the superbus clades were anhydrobiotic and also possessed robust freezing tolerance, along with a capacity to inhibit the growth and recrystallization of ice crystals. Unlike other endemic Antarctic nematodes, the life history traits of P. davidi do not show evidence of an evolved response to polar conditions. Thus we suggest that the colonization of Antarctica by P. davidi and of Surtsey by P. superbus may be examples of recent “ecological fitting” of freezing-tolerant anhydrobiotic propagules to the respective abiotic conditions in Ross Island and Surtsey.     

Cold tolerance in nematodes

Summary The nematodesTrichostrongylus colubriformis (J3),Ditylenchus dipsaci (J4) andPanagrellus silusae (adults) are freezing-susceptible but can avoid freezing by supercooling. Their mean supercooling points were –30.0±0.7°C forT. colubriformis, –21.7±0.7°C forD. dipsaci and –20.7±0.84°C forP. silusae. T. colubriformis andD. dipsaci could prevent seeding by external ice butP. silusae could not. The glycerol concentrations of these nematodes are considered to be too low to have a significant antifreeze effect.Abbreviations J3 3rd-stage juvenile - J4 4th stage juvenile - SEM standard error of the mean - T ₅₀ 50% survival temperature     

Variation and the phylogenetic utility of the large ribosomal subunit of mitochondrial DNA from the insect order Hymenoptera.

Nucleotide sequence variation from a 573-bp region of the mitochondrial 16S rRNA gene was determined for representative hymenopteran taxa. An overall bias in the distribution of A and T bases was observed from all taxa; however, the terebrants (parasitoids) displayed significantly lower AT ratios as well as a higher degree of strand asymmetry. Moreover, a strong positive correlation was observed between relative AT richness and sequence divergence, suggesting selection at the nucleotide level for A and T bases as well as functionality. Overall sequence difference ranged from 2.3 to 53.4%, with the maximum divergence between members of the two Hymenopteran suborders. These data were used in a phylogenetic analysis to illustrate the utility and degree of resolution provided by this information at various hierarchical levels within this taxonomically diverse order. Parsimony analysis revealed strong evidence for monophyly of the aculeates and the terebrants. Most noteworthy was a strongly supported clade containing the two terebrant superfamilies Icheumonoidea and Chalcidoidea. Conversely, high sequence divergence values resulted in instability at the base of the tree and limited resolution at the higher taxonomic levels. Nevertheless, these results do identify those taxonomic levels for which 16S rRNA sequences are phylogenetically informative.     

Bombesin-like immunoreactivity in the avian gut and its localisation to a distinct cell type

Summary The distribution of a bombesin-like immunoreactive peptide in the avian gastro-intestinal tract was analysed by combined radioimmunoassay and immunocytochemistry. Radioimmunoassay of tissue extracts showed that the largest quantities of bombesin-like immunoreactivity were present in the proventriculus (64.5±6.0 pmol/g) with smaller but still considerable amounts in the gizzard (40.0±6.0 pmol/g). Immunocytochemically the extractable bombesin-like immunoreactivity was localised in numerous endocrine cells. These, in the proventriculus, were found mainly in the deeper layers of the mucosa. Further study of these cells by the semi-thin/thin technique revealed the presence of characteristic secretory granules. The functional name BN is proposed for this cell type.