Preference and performance of Lepidoptera varies with tree age in juniper woodlands

1. As trees age, they undergo significant physiological and morphological changes. Nevertheless, tree ontogeny and its impacts on herbivores are often overlooked as determinants of plant–herbivore population dynamics and the strength of plant–herbivore interactions. 2. Juniperus (Cupressaceae) is a dominant, long‐lived conifer that serves as the sole host to a specialised assemblage of caterpillars. Over the past 150 years, several juniper species in western North America have expanded their geographic occupancy at local and regional scales, which has resulted in an increase in the number of immature trees on the landscape. Using assays in the laboratory, the effects of tree ontogeny on caterpillar performance and oviposition preference for two juniper specialist caterpillars, Callophrys gryneus (Lycaenidae) and Glena quinquelinearia (Geometridae), were examined. The study considered whether responses to tree ontogeny were consistent across caterpillar species and juniper host species. 3. Tree age was found to be a reliable predictor of caterpillar performance, with caterpillars developing more quickly and growing larger when fed foliage from young trees. Differences in the phytochemical diversity between foliage from trees of different ages might help to explain observed differences in caterpillar performance. Interestingly, the specialist butterfly, C. gryneus, displayed an oviposition preference for foliage from old‐growth Juniperus osteosperma trees, despite the fact that larvae of this species performed poorly on older trees. 4. It is concluded that young juniper trees are an important resource for the specialised Lepidopteran community and that tree ontogeny is an important component of intraspecific variation, which contributes to the structure of plant–herbivore communities.     

The Sodium/Proton Exchanger NHE8 Regulates Late Endosomal Morphology and Function

The pH and lumenal environment of intracellular organelles is considered essential for protein sorting and trafficking through the cell. We provide the first evidence that a mammalian NHE sodium (potassium)/proton exchanger, NHE8, plays a key role in the control of protein trafficking and endosome morphology. At steady state, the majority of epitope-tagged NHE8 was found in the trans-Golgi network of HeLa M-cells, but a proportion was also localized to multivesicular bodies (MVBs). Depletion of NHE8 in HeLa M-cells with siRNA resulted in the perturbation of MVB protein sorting, as shown by an increase in epidermal growth factor degradation. Additionally, NHE8-depleted cells displayed striking perinuclear clustering of endosomes and lysosomes, and there was a ninefold increase in the cellular volume taken up by LAMP1/LBPA-positive, dense MVBs. Our data points to a role for the ion exchange activity of NHE8 being required to maintain endosome morphology, as overexpression of a nonfunctional point mutant protein (NHE8 E225Q) resulted in phenotypes similar to those seen after siRNA depletion of endogenous NHE8. Interestingly, we found that depletion of NHE8, despite its function as a sodium (potassium)/proton antiporter, did not affect the overall pH inside dense MVBs.     

Functional changes in the structure of the SRP GTPase on binding GDP and Mg2+GDP.

Ffh is a component of a bacterial ribonucleoprotein complex homologous to the signal recognition particle (SRP) of eukaryotes. It comprises three domains that mediate both binding to the hydrophobic signal sequence of the nascent polypeptide and the GTP-dependent interaction of Ffh with a structurally homologous GTPase of the SRP receptor. The X-ray structures of the two-domain 'NG' GTPase of Ffh in complex with Mg2+GDP and GDP have been determined at 2.0 A resolution. The structures explain the low nucleotide affinity of Ffh and locate two regions of structural mobility at opposite sides of the nucleotide-binding site. One of these regions includes highly conserved sequence motifs that presumably contribute to the structural trigger signaling the GTP-bound state. The other includes the highly conserved interface between the N and G domains, and supports the hypothesis that the N domain regulates or signals the nucleotide occupancy of the G domain.     

A statistical method for correlating tRNA sequence with amino acid specificity.

A statistical method for finding the nucleotide positions in tRNA sequences that correlate with amino acid specificity has been developed. The procedure involves finding the subset of nucleotide positions and groups of positions where the marginal density of one amino acid tRNA class does not overlap that of any other amino acid class. The procedure is an application of a statistical method known as the Expectation Maximization algorithm.     

Mysterious bio-duck sound attributed to the Antarctic minke whale (Balaenoptera bonaerensis)

For decades, the bio-duck sound has been recorded in the Southern Ocean, but the animal producing it has remained a mystery. Heard mainly during austral winter in the Southern Ocean, this ubiquitous sound has been recorded in Antarctic waters and contemporaneously off the Australian west coast. Here, we present conclusive evidence that the bio-duck sound is produced by Antarctic minke whales (Balaenoptera bonaerensis). We analysed data from multi-sensor acoustic recording tags that included intense bio-duck sounds as well as singular downsweeps that have previously been attributed to this species. This finding allows the interpretation of a wealth of long-term acoustic recordings for this previously acoustically concealed species, which will improve our understanding of the distribution, abundance and behaviour of Antarctic minke whales. This is critical information for a species that inhabits a difficult to access sea-ice environment that is changing rapidly in some regions and has been the subject of contentious lethal sampling efforts and ongoing international legal action.     

Über den Einfluß des Zinks auf das Pflanzenwachstum

Ohne Zusammenfassung     

Occurrence of multiple-antibiotic-resistant enteric bacteria in domestic sewage and oxidation lagoons

The coliform bacterial population in the Grand Forks, N.Dak. sewage system was examined for multiple-antibiotic-resistant organisms over a 1-year period. Multiple-antibiotic-resistant coliforms were found to be common in the sewage, and their numbers remained fairly constant relative to the total coliform population throughout the year. Resistance to kanamycin, tetracycline, and ampicillin was found to be transferable at variable rates. Transfer rates were found to be temperature sensitive and were optimal at 35 degrees C. Although 75% of the multiple-antibiotic-resistant coliforms were capable of transferring resistance at some level, only 25% were capable of transferring resistance at rates greater than 10(-3) transconjugants per initial donor.     

Release of pituitary melanocyte-stimulating hormone by the oxytocin fragment, H-Cys-Tyr-Ile-Gln-Asn-Oh

The effect of the pentapeptide H-Cys-Tyr-Ile-Gln-Asn-OH to act like melanocyte-stimulating hormone-releasing factor (MSH-RF) was studied. This peptide decreases at ng amounts the MSH content of the rat pituitary and increases plasma MSH concentration. This agent also stimulates the release of MSH in animals with eminence lesion, indicating a direct action of the pentapeptide on the gland.     

Inhibition of GSK-3β Rescues the Impairments in Bone Formation and Mechanical Properties Associated with Fracture Healing in Osteoblast Selective Connexin 43 Deficient Mice

Connexin 43 (Cx43) is the most abundant gap junction protein in bone and is required for osteoblastic differentiation and bone homeostasis. During fracture healing, Cx43 is abundantly expressed in osteoblasts and osteocytes, while Cx43 deficiency impairs bone formation and healing. In the present study we selectively deleted Cx43 in the osteoblastic lineage from immature osteoblasts through osteocytes and tested the hypothesis that Cx43 deficiency results in delayed osteoblastic differentiation and impaired restoration of biomechanical properties due to attenuated β-catenin expression relative to wild type littermates. Here we show that Cx43 deficiency results in alterations in the mineralization and remodeling phases of healing. In Cx43 deficient fractures the mineralization phase is marked by delayed expression of osteogenic genes. Additionally, the decrease in the RankL/ Opg ratio, osteoclast number and osteoclast size suggest decreased osteoclast bone resorption and remodeling. These changes in healing result in functional deficits as shown by a decrease in ultimate torque at failure. Consistent with these impairments in healing, β-catenin expression is attenuated in Cx43 deficient fractures at 14 and 21 days, while Sclerostin (Sost) expression, a negative regulator of bone formation is increased in Cx43cKO fractures at 21 days, as is GSK-3β, a key component of the β-catenin proteasomal degradation complex. Furthermore, we show that alterations in healing in Cx43 deficient fractures can be rescued by inhibiting GSK-3β activity using Lithium Chloride (LiCl). Treatment of Cx43 deficient mice with LiCl restores both normal bone formation and mechanical properties relative to LiCl treated WT fractures. This study suggests that Cx43 is a potential therapeutic target to enhance fracture healing and identifies a previously unknown role for Cx43 in regulating β-catenin expression and thus bone formation during fracture repair.