Telomere length in relation to colour polymorphism across life stages in the tawny owl

Telomere erosion has been proposed to be tightly associated with senescence, environmental stressors and life history trade‐offs. How telomere dynamics vary across life stages and especially in relation to (heritable) phenotypic traits is still unclear. The tawny owl Strix aluco display a highly heritable melanin‐based colour polymorphism, a grey and a brown morph, linked to several fitness traits including morph‐specific telomere dynamics. As adults, brown tawny owls have shorter relative telomere length (RTL) and exhibit faster telomere shortening rate than grey owls. Here we test if these morph‐specific telomere dynamics emerge already during growth, or if they are induced only in adult life through differential physiological costs associated with the life history of the morphs. We analysed RTL from 287 tawny owl offspring and 81 first breeding adults to evaluate at what life stage morph‐specific patterns emerge. We found no differences in RTL between the two morphs during the nestling period nor at the first breeding attempt. Sex, brood size or size rank in the nest did not affect offspring RTL. Among first‐breeders, females had shorter telomeres than males suggesting a sampling‐time dependent difference in reproductive costs between sexes, due to the prominent sex roles in tawny owls in the early nestling period. The probability to return to breed after the first breeding attempt was not affected by RTL, sex or colour morph. The lack of morph‐specific difference in RTL among nestlings and first breeders suggests that previously observed morph‐specific differences in RTL dynamics in adults emerge at the onset of the breeding career and is likely due to different physiological profiles and life‐history strategies adopted by adults. We conclude that different telomere dynamics and senescence patterns among highly heritable phenotypes (colour morphs) are likely to be a result of differential costs of reproduction and self‐maintenance.     

Landscape structure shapes activity levels and composition of aerial insectivorous bats at different spatial scales

Biodiversity and Conservation - Tropical forests are being lost and modified at an unprecedented rate, with extant biodiversity increasingly restricted to human-modified landscapes. Resulting...     

The N2A region of titin has a unique structural configuration

The N2A segment of titin is a main signaling hub in the sarcomeric I-band that recruits various signaling factors and processing enzymes. It has also been proposed to play a role in force production through its Ca²⁺-regulated association with actin. However, the molecular basis by which N2A performs these functions selectively within the repetitive and extensive titin chain remains poorly understood. Here, we analyze the structure of N2A components and their association with F-actin. Specifically, we characterized the structure of its Ig domains by elucidating the atomic structure of the I81-I83 tandem using x-ray crystallography and computing a homology model for I80. Structural data revealed these domains to present heterogeneous and divergent Ig folds, where I81 and I83 have unique loop structures. Notably, the I81-I83 tandem has a distinct rotational chain arrangement that confers it a unique multi-domain topography. However, we could not identify specific Ca²⁺-binding sites in these Ig domains, nor evidence of the association of titin N2A components with F-actin in transfected C2C12 myoblasts or C2C12-derived myotubes. In addition, F-actin cosedimentation assays failed to reveal binding to N2A. We conclude that N2A has a unique architecture that predictably supports its selective recruitment of binding partners in signaling, but that its mechanical role through interaction with F-actin awaits validation.     

Possible Links Between Stress Defense and the Tricarboxylic Acid (TCA) Cycle in Francisella Pathogenesis

Francisella tularensis is a highly infectious bacterium causing the zoonotic disease tularemia. In vivo, this facultative intracellular bacterium survives and replicates mainly in the cytoplasm of infected cells. We have recently identified a genetic locus, designated moxR that is important for stress resistance and intramacrophage survival of F. tularensis. In the present work, we used tandem affinity purification coupled to mass spectrometry to identify in vivo interacting partners of three proteins encoded by this locus: the MoxR-like ATPase (FTL_0200), and two proteins containing motifs predicted to be involved in protein–protein interactions, bearing von Willebrand A (FTL_0201) and tetratricopeptide (FTL_0205) motifs. The three proteins were designated here for simplification, MoxR, VWA1, and TPR1, respectively. MoxR interacted with 31 proteins, including various enzymes. VWA1 interacted with fewer proteins, but these included the E2 component of 2-oxoglutarate dehydrogenase and TPR1. The protein TPR1 interacted with one hundred proteins, including the E1 and E2 subunits of both oxoglutarate and pyruvate dehydrogenase enzyme complexes, and their common E3 subunit. Remarkably, chromosomal deletion of either moxR or tpr1 impaired pyruvate dehydrogenase and oxoglutarate dehydrogenase activities, supporting the hypothesis of a functional role for the interaction of MoxR and TPR1 with these complexes. Altogether, this work highlights possible links between stress resistance and metabolism in F. tularensis virulence.Francisella tularensis is responsible for the disease tularamia in a large number of animal species. This highly infectious bacterial pathogen can be transmitted to humans in numerous ways (1, 2, 3), including direct contact with sick animals, inhalation, ingestion of contaminated water or food, or by bites from ticks, mosquitoes, or flies. Four different subspecies (subsp.) of F. tularensis that differ in virulence and geographic distribution exist, designated subsp. tularensis (type A), subsp. holarctica (type B), subsp. Novicida, and subsp. mediasiatica, respectively. F. tularensis subsp. tularensis is the most virulent subspecies causing a severe disease in humans, whereas F. tularensis subsp. holarctica causes a similar disease but of less severity (4). Because of its high infectivity and lethality, F. tularensis is considered a potential bioterrorism agent (5).F. tularensis is able to survive and to replicate in the cytoplasm of a variety of infected cells, including macrophages. To resist this stressful environment, the bacterium must have developed stress resistance mechanisms, most of which are not yet well characterized. We recently reported the identification of a novel genetic locus that is important for stress resistance and intracellular survival of F. tularensis (6). This locus was designated moxR because the first gene FTL_0200, encodes a protein belonging to the AAA+ ATPase of the MoxR family ((7) and references therein). The data obtained in that first study had led us to suggest that the F. tularensis MoxR-like protein might constitute, in combination with other proteins of the locus, a chaperone complex contributing to F. tularensis pathogenesis.To further validate this hypothesis and expand our initial observations, we here decided to perform tandem affinity purification (TAP),¹ using a dual affinity tag approach coupled to mass spectroscopy analyses (8), to identify proteins interacting in vivo with three proteins encoded by the proximal portion of the moxR locus. For this, we chose as baits: the MoxR-like protein (FTL_0200) and two proteins bearing distinct motifs possibly involved in protein–protein interactions, FTL_0201 (Von Willebrand Factor Type A domain, or VWA) and FTL_0205 (tetratrichopeptide repeat or TPR). The three proteins were designated here for simplification, MoxR, VWA1, and TPR1; and the corresponding genes moxR, vwa1, and tpr1, respectively.VWA domains are present in all three kingdoms of life. They consist of a β-sheet sandwiched by multiple α helices. Frequently, VWA domain-containing proteins function in multiprotein complexes (9). TPR typically contain 34 amino acids. Many three-dimensional structures of TPR domains have been solved, revealing amphipathic helical structures (10). TPR-containing proteins are also found in all kingdoms of life. They can be involved in a variety of functions, and generally mediate protein–protein interactions. In the past few years, several TPR-related proteins have been shown to be involved in virulence mechanisms in pathogenic bacteria ((11) and references therein).Our proteomic approach allowed us to identify a series of protein interactants for each of the three moxR-encoded proteins. Remarkably, the protein TPR1 interacted with all the subunits of the pyruvate dehydrogenase (PDH) and 2-oxoglutarate dehydrogenase (OGDH) complexes. Furthermore, inactivation of tpr1 also severely impaired the activities of these two enzymes. Inactivation of tpr1 affected bacterial resistance to several stresses (and in particular oxidative stress), intramacrophagic bacterial multiplication and bacterial virulence in the mouse model. Functional implications and possible relationship between bacterial metabolism, stress defense, and bacterial virulence are discussed.     

Ross Sea Mollusca from the Latitudinal Gradient Program: R/V Italica 2004 Rauschert dredge samples

Information regarding the molluscs in this dataset is based on the Rauschert dredge samples collected during the Latitudinal Gradient Program (LGP) on board the R/V “Italica” in the Ross Sea (Antarctica) in the austral summer 2004. A total of 18 epibenthic dredge deployments/samplings have been performed at four different locations at depths ranging from 84 to 515m by using a Rauschert dredge with a mesh size of 500μm. In total 8,359 specimens have been collected belonging to a total of 161 species. Considering this dataset in terms of occurrences, it corresponds to 505 discrete distributional records (incidence data). Of these, in order of abundance, 5,965 specimens were Gastropoda (accounting for 113 species), 1,323 were Bivalvia (accounting for 36 species), 949 were Aplacophora (accounting for 7 species), 74 specimens were Scaphopoda (3 species), 38 were Monoplacophora (1 species) and, finally, 10 specimens were Polyplacophora (1 species). This data set represents the first large-scale survey of benthic micro-molluscs for the area and provides important information about the distribution of several species, which have been seldom or never recorded before in the Ross Sea. All vouchers are permanently stored at the Italian National Antarctic Museum (MNA), Section of Genoa, enabling future comparison and crosschecking. This material is also currently under study, from a molecular point of view, by the barcoding project “BAMBi” (PNRA 2010/A1.10).     

A standardized laboratory and surgical method for in vitro culture isolation and expansion of primary human Tenon’s fibroblasts

Good manufacturing practices guidelines require safer and standardized cell substrates especially for those cell therapy products to treat ocular diseases where fibroblasts are used as feeder layers. However, if these are unavailable for stem cells culturing, murine fibroblasts are regularly used, raising critical issues as accidentally transplanting xenogenous graft and adversely affecting stem cell clinical trials. Moreover, human fibroblasts play a significant role in testing novel ophthalmologic drugs. Accordingly, we developed a standardized laboratory and surgical approach to isolate normal and undamaged Tenon’s fibroblasts to implement the setting up of banks for both stem cells-based ocular cell therapy and in vitro drug testing. A 2–3 cm² undamaged Tenon’s biopsy was surgically obtained from 28 patients without mutually correlated ocular diseases. Nineteen dermal biopsies were used as control. Fibroblasts were isolated with or without collagenase, cultured in autologous, fetal bovine or AB serum, tested for viability by trypan blue, vimentin expression and standardized until passage 6. Successful Tenon’s fibroblasts isolation was age dependent (P = 0.001) but not sex, pathology or surgery related. A significant rate of successful cultures were obtained when biopsies were not digested by collagenase (P = 0.013). Moreover, cultures in autologous or fetal bovine serum had comparable proliferative properties (P = 0.77; P = 0.82). Through our surgical and laboratory standardized procedure, we elucidated for the first time key points of this human primary culture system, the role of the autologous serum, comparing Tenon’s and dermal fibroblasts. Our protocol may be clinically useful to reduce the risk above mentioned and may be potentially more effective for ophthalmological clinical purposes.     

Genomic analysis reveals the biotechnological ability of Enterococcus italicus to produce glutathione

Through the analysis of the recently available genome shotgun sequence of Enterococcus italicus DSM 15952^T type strain (Accession PRJNA61487, ID 61487), we found the presence of a gene encoding a bifunctional enzyme, termed γ-GCS-GS or GshF, involved in glutathione production and not influenced by feedback inhibition. The gshF gene exhibited high nucleotide and amino acid sequence similarity to other reported sequences from the Enterococcus genus and was constitutively expressed both in osmotic shock or in common cultural conditions. Several experimental studies concerning the culture medium, physiological stress, cell extract obtainment, and scaling-up showed that in selected conditions E. italicus was able to accumulate up to 250 μM of intracellular glutathione, which represented the main thiol group present into the cells. This is the first report regarding the production of glutathione by E. italicus, a species that could be used as a safe adjunct culture for glutathione-enriched dairy foods.