A novel protein,sperm head and tail associated protein (SHTAP), interacts with cysteine‐rich secretory protein 2 (CRISP2) during spermatogenesis in the mouse

Background information. CRISP2 (cysteine‐rich secretory protein 2) is a sperm acrosome and tail protein with the ability to regulate Ca²⁺ flow through ryanodine receptors. Based on these properties, CRISP2 has a potential role in fertilization through the regulation of ion signalling in the acrosome reaction and sperm motility. The purpose of the present study was to determine the expression, subcellular localization and the role in spermatogenesis of a novel CRISP2‐binding partner, which we have designated SHTAP (sperm head and tail associated protein). Results. Using yeast two‐hybrid screens of an adult testis expression library, we identified SHTAP as a novel mouse CRISP2‐binding partner. Sequence analysis of all Shtap cDNA clones revealed that the mouse Shtap gene is embedded within a gene encoding the unrelated protein NSUN4 (NOL1/NOP2/Sun domain family member 4). Five orthologues of the Shtap gene have been annotated in public databases. SHTAP and its orthologues showed no significant sequence similarity to any known protein or functional motifs, including NSUN4. Using an SHTAP antiserum, multiple SHTAP isoforms (～20–87 kDa) were detected in the testis, sperm, and various somatic tissues. Interestingly, only the ～26 kDa isoform of SHTAP was able to interact with CRISP2. Furthermore, yeast two‐hybrid assays showed that both the CAP (CRISP/antigen 5/pathogenesis related‐1) and CRISP domains of CRISP2 were required for maximal binding to SHTAP. SHTAP protein was localized to the peri‐acrosomal region of round spermatids, and the head and tail of the elongated spermatids and sperm tail where it co‐localized with CRISP2. During sperm capacitation, SHTAP and the SHTAP—CRISP2 complex appeared to be redistributed within the head. Conclusions. The present study is the first report of the identification, annotation and expression analysis of the mouse Shtap gene. The redistribution observed during sperm capacitation raises the possibility that SHTAP and the SHTAP—CRISP2 complex play a role in the attainment of sperm functional competence.     

Interactive effects of pests increase seed yield

Loss in seed yield and therefore decrease in plant fitness due to simultaneous attacks by multiple herbivores is not necessarily additive, as demonstrated in evolutionary studies on wild plants. However, it is not clear how this transfers to crop plants that grow in very different conditions compared to wild plants. Nevertheless, loss in crop seed yield caused by any single pest is most often studied in isolation although crop plants are attacked by many pests that can cause substantial yield losses. This is especially important for crops able to compensate and even overcompensate for the damage. We investigated the interactive impacts on crop yield of four insect pests attacking different plant parts at different times during the cropping season. In 15 oilseed rape fields in Sweden, we estimated the damage caused by seed and stem weevils, pollen beetles, and pod midges. Pest pressure varied drastically among fields with very low correlation among pests, allowing us to explore interactive impacts on yield from attacks by multiple species. The plant damage caused by each pest species individually had, as expected, either no, or a negative impact on seed yield and the strongest negative effect was caused by pollen beetles. However, seed yield increased when plant damage caused by both seed and stem weevils was high, presumably due to the joint plant compensatory reaction to insect attack leading to overcompensation. Hence, attacks by several pests can change the impact on yield of individual pest species. Economic thresholds based on single species, on which pest management decisions currently rely, may therefore result in economically suboptimal choices being made and unnecessary excessive use of insecticides.     

Effective treatment of inflammatory disease models with exosomes derived from dendritic cells genetically modified to express IL-4

In this study, we demonstrate that genetically modified bone marrow-derived dendritic cells (DC) and exosomes derived from the DC, expressing either secreted IL-4 or membrane-bound IL-4, can reduce the severity and the incidence of established collagen-induced arthritis and inhibit inflammation of delayed-type hypersensitivity (DTH) in mice. The ability of the DC and DC-derived exosomes to suppress the DTH response was MHC class II and, in part, Fas ligand/Fas dependent. The DC-derived exosomes were internalized by CD11c(+) DC in the dermis at the site of injection and in the draining lymph node as well as by CD11c(+) DC and F4/80(+) macrophages in the spleen. Moreover, adoptive transfer of CD11c(+) or CD3(+) splenic cells from mice treated with exosomes showed significant reduction of footpad swelling in the DTH model. These results demonstrate that administration of DC/IL-4 or exosomes derived from DC/IL-4 are able to modulate the activity of APC and T cells in vivo through a MHC class II and partly Fas ligand/Fas-dependent mechanism, resulting in effective treatment of established collagen-induced arthritis and suppression of the DTH inflammatory response. Thus, APC-derived exosomes could be used therapeutically for the treatment of autoimmune disease and inflammatory disorders.     

Specific interactions with intra- and intermolecular G-quadruplex DNA structures by hydrosoluble coronene derivatives: a new class of telomerase inhibitors

In developing G-quadruplex interactive telomerase inhibitors two main features have to be taken into account: the hydrophobic interactions with the G-quartet plane and the electrostatic interactions with the negatively charged phosphates of the four grooves. In this paper, we report the synthesis of four hydrosoluble coronene derivatives, which are characterized by a large hydrophobic aromatic core and four orthogonal hydrophilic side chains. We have studied their ability to induce both inter- and intramolecular G-quadruplex structures and found a significant selectivity of all the coronene derivatives for the intramolecular G-quadruplex. The efficiency in inhibiting human telomerase has been evaluated in a cell-free system and the experimental results correlate with the relative affinities of these compounds for the G-quadruplex monomeric structure, as derived by molecular modelling simulations. Thus, the coronene derivatives can be considered as a new class of telomerase inhibitors, although further investigations are surely necessary to fully exploit their features.     

Increased expression of titin in mouse gastrocnemius muscle in response to an endurance-training program

Titin, a sarcomeric giant protein, plays crucial roles in muscle assembly, elasticity and stability. Little is known about titin adaptation to endurance exercise. We studied the effects of endurance training on titin expression in mouse gastrocnemius muscles (MGM). Sixty-three ten-week-old male Swiss mice were divided into seven groups. Four groups were composed of untrained control animals (C0, C15, C30, C45) instead the other three included mice trained for 15 (T15), 30 (T30) and 45 (T45) days by treadmill. The training protocol was mainly aerobic, characterized by moderate-intensity, rhythmic and continuous exercises. Titin expression was determined by immunohistochemistry on MGM sections. Results revealed a significant reduction in body weight of the T45 mice and a significant increase in titin expression (% titin immunoreactivity median [range] = 41.11 [20-60] vs. 30.00 [10-50]). It is postulated that the up-regulation of titin expression is an adaptative mechanism to increase muscle elasticity and stability in response to the high number of stretch-shorten cycles during endurance training. Such a mechanism may be important for minimizing muscle energy consumption and improving performance during running.     

The chimerical genome of Isla del Coco feral pigs (Costa Rica), an isolated population since 1793 but with remarkable levels of diversity

The history of domestic species and of their wild ancestors is not a simple one, and feral processes can clarify key aspects of this history, including the adaptive processes triggered by new environments. Here, we provide a comprehensive genomic study of Isla del Coco (Costa Rica) feral pigs, a unique population that was allegedly founded by two individuals and has remained isolated since 1793. Using SNP arrays and genome sequencing, we show that Cocos pigs are hybrids between Asian and European pigs, as are modern international pig breeds. This conclusively shows that, as early as the 18th century, British vessels were loading crossbred pigs in Great Britain and transporting them overseas. We find that the Y chromosome has Asian origin, which has not been reported in any international pig breed. Chinese haplotypes seem to have been transmitted independently between Cocos and other pig breeds, suggesting independent introgression events and a complex pattern of admixing. Although data are compatible with a founder population of N = 2, variability levels are as high in Cocos pigs as in international pig breeds (~1.9 SNPs/kb) and higher than in European wild boars or local breeds (~1.7 SNPs/kb). Nevertheless, we also report a 10‐Mb region with a marked decrease in variability across all samples that contains four genes (CPE, H3F3C, SC4MOL and KHL2) previously identified as highly differentiated between wild and domestic pigs. This work therefore illustrates how feral population genomic studies can help to resolve the history of domestic species and associated admixture events.     

Titin Domains Progressively Unfolded by Force Are Homogenously Distributed along the Molecule

Titin is a giant filamentous protein of the muscle sarcomere in which stretch induces the unfolding of its globular domains. However, the mechanisms of how domains are progressively selected for unfolding and which domains eventually unfold have for long been elusive. Based on force-clamp optical tweezers experiments we report here that, in a paradoxical violation of mechanically driven activation kinetics, neither the global domain unfolding rate, nor the folded-state lifetime distributions of full-length titin are sensitive to force. This paradox is reconciled by a gradient of mechanical stability so that domains are gradually selected for unfolding as the magnitude of the force field increases. Atomic force microscopic screening of extended titin molecules revealed that the unfolded domains are distributed homogenously along the entire length of titin, and this homogeneity is maintained with increasing overstretch. Although the unfolding of domains with progressively increasing mechanical stability makes titin a variable viscosity damper, the spatially randomized variation of domain stability ensures that the induced structural changes are not localized but are distributed along the molecule''s length. Titin may thereby provide complex safety mechanims for protecting the sarcomere against structural disintegration under excessive mechanical conditions.