A functional genetic marker for apple red skin coloration across different environments

The red skin color desired by most apple consumers is not easy to achieve in warm climates, as the expression of MYB10, which regulates red pigmentation in apple, is influenced negatively by high temperatures. We describe the development and validation of a genetic marker for red skin coloration that effectively predicts color in a warm summer environment in Spain, as well as more temperate climates in New Zealand and Italy. Following the determination of a major-effect quantitative trait locus (QTL) controlling red skin coloration on linkage group (LG)9, using four segregating populations grown in New Zealand, and screened using the IRSC apple 8-K single-nucleotide polymorphism (SNP) array, the most significant SNP marker (ss475879531) was transformed into a marker suitable for use in a real-time PCR assay. This marker was validated using five apple seedling populations growing in a warm summer environment in Spain, demonstrating that the marker system efficiently predicts red skin coloration and can be used for marker assisted selection, even under conditions considered adverse for skin color development.     

The ATM Signaling Cascade Promotes Recombination-Dependent Pachytene Arrest in Mouse Spermatocytes

Most mutations that compromise meiotic recombination or synapsis in mouse spermatocytes result in arrest and apoptosis at the pachytene stage of the first meiotic prophase. Two main mechanisms are thought to trigger arrest: one independent of the double-strand breaks (DSBs) that initiate meiotic recombination, and another activated by persistent recombination intermediates. Mechanisms underlying the recombination-dependent arrest response are not well understood, so we sought to identify factors involved by examining mutants deficient for TRIP13, a conserved AAA+ ATPase required for the completion of meiotic DSB repair. We find that spermatocytes with a hypomorphic Trip13 mutation (Trip13^mod/mod) arrest with features characteristic of early pachynema in wild type, namely, fully synapsed chromosomes without incorporation of the histone variant H1t into chromatin. These cells then undergo apoptosis, possibly in response to the arrest or in response to a defect in sex body formation. However, TRIP13-deficient cells that additionally lack the DSB-responsive kinase ATM progress further, reaching an H1t-positive stage (i.e., similar to mid/late pachynema in wild type) despite the presence of unrepaired DSBs. TRIP13-deficient spermatocytes also progress to an H1t-positive stage if ATM activity is attenuated by hypomorphic mutations in Mre11 or Nbs1 or by elimination of the ATM-effector kinase CHK2. These mutant backgrounds nonetheless experience an apoptotic block to further spermatogenic progression, most likely caused by failure to form a sex body. DSB numbers are elevated in Mre11 and Nbs1 hypomorphs but not Chk2 mutants, thus delineating genetic requirements for the ATM-dependent negative feedback loop that regulates DSB numbers. The findings demonstrate for the first time that ATM-dependent signaling enforces the normal pachytene response to persistent recombination intermediates. Our work supports the conclusion that recombination defects trigger spermatocyte arrest via pathways than are genetically distinct from sex body failure-promoted apoptosis and confirm that the latter can function even when recombination-dependent arrest is inoperative. Implications of these findings for understanding the complex relationships between spermatocyte arrest and apoptosis are discussed.     

Targeting of substance P induces cancer cell death and decreases the steady state of EGFR and Her2

NK1 is a tachykinin receptor highly relevant to tumorigenesis and metastasis development in breast cancer and other carcinomas. Despite the substantial efforts done to develop potent NK1 receptor antagonists, none of these antagonists had shown good antitumor activity in clinical trials. Now, we have tested the effect of inhibition of the neuropeptide Substance P (SP), a NK1 ligand, as a potential therapeutic approach in cancer. We found that the inhibition of SP with antibodies strongly inhibit cell growth and induce apoptosis in breast, colon, and prostate cancer cell lines. These effects were accompained by a decrease in the mitogen-activated kinase singaling pathway. Interestingly, in some cell lines SP abrogation decreased the steady state of Her2 and EGFR, suggesting that SP-mediated signaling is important for the basal activity of these ErbB receptors. In consequence, we observed a blockade of the cell cycle progression and the inhibition of several cell cycle-related proteins including mTOR. SP inhibition also induced cell death in cell lines resistant to Lapatinib and Trastuzumab that have increased levels of active Her2, suggesting that this therapeutic approach could be also effective for those cancers resistant to current anti-ErbB therapies. Thus, we propose a new therapeutic strategy for those cancers that express NK1 receptor and/or other tachykinin receptors, based in the immuno-blockade of the neuropeptide SP.     

Demography of the invasive geophyte Oxalis pes-caprae across a Mediterranean island

BACKGROUND AND AIMS: Success during the early stages of the life-history of alien plants is essential for invasion to occur. The reproductive components of plant invaders have mostly been studied in species reproducing sexually but little is known about invaders that depend exclusively on vegetative reproduction. In this paper, the importance of the different recruitment stages on population growth is quantified and, thus, the invasion potential of the South African annual geophyte Oxalis pes-caprae invading Mediterranean ecosystems is assessed. METHODS: Tests and experiments were conducted across Menorca (Balearic Islands) to analyse the spatial variability of Oxalis pes-caprae reproductive components (i.e. bulb production, bulb bank, bulb predation, bulb mortality, bulb dormancy, bulb germination, plant establishment and survival). KEY RESULTS: Oxalis pes-caprae has a transient bulb bank that remains dormant in the soil during summer. High levels of bulb predation after dispersal, followed by bulb mortality during summer or a failure to germinate in autumn were the most critical factors limiting plant establishment. Bulb germination was high. However, plant establishment and bulb production is constrained by intraspecific competition, but is not affected by soil disturbance. No symptoms of spatial discordance could be found between recruitment stages because the spatial variability of the life cycle was extremely low at all the scales examined (i.e. among populations, habitats and microsites). It was estimated that, on average, 4 % of bulbs can become plants the following year and the field rate of population increase (lambda) to be 0.08. CONCLUSIONS: The results suggest that invasion is constrained by post-dispersal bulb predation, loss of viability of the propagule bank due to summer drought and high intraspecific competition. However, a high spatial concordance between recruitment stages and probably a high propagule pressure due to human and livestock bulb dispersal determine the success of this invader across Menorca Island.     

Effect of venipuncture site on hematologic and serum biochemical parameters in marginated tortoise (Testudo marginata)

Blood samples were obtained from the dorsal coccygeal vein and the brachial vein of five adult (four females and one male) and two subadult males of marginated tortoise (Testudo marginata) and hematologic and biochemical parameters were compared. Significant differences were found for red blood cell count, hematocrit, hemoglobin concentration, total proteins, uric acid, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, alkaline phosphatase, calcium, and phosphorus, which were greater in the brachial vein samples. Hemodilution due to lymph was observed when collecting blood from the dorsal coccygeal vein, and it is thought to be the cause of the differences found. This research documented that the brachial vein is a more reliable and consistent venipuncture site than dorsal coccygeal vein in marginated tortoise.     

Acute stress-induced tissue injury in mice: differences between emotional and social stress

Emotional stress affects cellular integrity in many tissues including the heart. Much less is known about the effects of social stress. We studied the effect of emotional (immobilization with or without cold exposure) or social (intermale confrontation) stress in mice. Tissue injury was measured by means of the release of enzyme activities to blood plasma: lactate dehydrogenase (LDH), creatine kinase (CK), aspartate transaminase (AST), and alanine transaminase (ALT). Tape-immobilization increased all these activities in the plasma. AST-ALT ratio was also increased in these animals. Electrophoretic analysis of CK isoenzymes showed the appearance of CK-MB. These results indicate that the heart was injured in immobilized mice. Analysis of LDH isoenzymes and measurement of alpha-hydroxybutyrate dehydrogenase (HBDH) activity suggests that other tissues, in addition to the heart, contribute to the increase in plasma LDH activity. Restraint in small cylinders increased plasma LDH, CK, AST, and ALT activities, but to lower levels than in tape immobilization. Because the decrease in liver glycogen and the increase in plasma epidermal growth factor (EGF) were also smaller in restraint than in the tape-immobilization model of emotional stress, we conclude that the former is a less intense stressor than the latter. Cold exposure during the restraint period altered the early responses to stress (it enhanced liver glycogen decrease, but abolished the increase in plasma EGF concentration). Cold exposure during restraint enhanced heart injury, as revealed by the greater increase in CK and AST activities. Intermale confrontation progressively decreased liver glycogen content. Plasma EGF concentration increased (to near 100 nM from a resting value of 0.1 nM) until 60 minutes, and decreased thereafter. Confrontation also affected cellular integrity in some tissues, as indicated by the rise in plasma LDH activity. However, in this type of stress, the heart appeared to be specifically protected because there was no increase in plasma CK activity, and both AST and ALT increased, but the AST-ALT ratio remained constant. Habituation to restraint (1 h/d, 4 days) made mice resistant to restraint-induced tissue injury as indicated by the lack of an increase in plasma LDH, CK, AST, or ALT activities. Similar general protection against homotypic stress-induced injury was observed in mice habituated to intermale confrontation.     

Target identification of the novel antiobesity agent tungstate in adipose tissue from obese rats

Adipose tissue plays an active role in the development of obesity, and thus characterization of the molecular changes related to obesity in this tissue is a priority. Recently, we identified tungstate as a potent body weight reducing agent in obese animals, adipose tissue being one of the targets of its action. In this study a proteomics approach combining 2-DE and MS was used to identify proteins associated with obesity and targets of tungstate in white adipose tissue. Twenty-nine proteins were found differentially expressed between lean and diet-induced obese rats. Expression changes in transferrin, vimentin, vinculin, peroxiredoxins, Rho-GTP dissociation inhibitor, grifin, guanine deaminase and 3-phosphoglycerate dehydrogenase were associated here for the first time with obesity. Furthermore, tungstate treatment of obese rats reverted expression changes of 70% of the proteins modulated by obesity and another ten proteins were regulated by tungstate independently of the body weight reduction. The results suggest that the tungstate antiobesity effect can be mediated by the modulation of cellular structure, metabolism, redox state and signalling processes in adipose tissue. These findings open new avenues for the study of the aetiology of obesity and its treatment.     

Motor Cost Influences Perceptual Decisions

Perceptual decision making has been widely studied using tasks in which subjects are asked to discriminate a visual stimulus and instructed to report their decision with a movement. In these studies, performance is measured by assessing the accuracy of the participants’ choices as a function of the ambiguity of the visual stimulus. Typically, the reporting movement is considered as a mere means of reporting the decision with no influence on the decision-making process. However, recent studies have shown that even subtle differences of biomechanical costs between movements may influence how we select between them. Here we investigated whether this purely motor cost could also influence decisions in a perceptual discrimination task in detriment of accuracy. In other words, are perceptual decisions only dependent on the visual stimulus and entirely orthogonal to motor costs? Here we show the results of a psychophysical experiment in which human subjects were presented with a random dot motion discrimination task and asked to report the perceived motion direction using movements of different biomechanical cost. We found that the pattern of decisions exhibited a significant bias towards the movement of lower cost, even when this bias reduced performance accuracy. This strongly suggests that motor costs influence decision making in visual discrimination tasks for which its contribution is neither instructed nor beneficial.