The Fanconi anemia ortholog FANCM ensures ordered homologous recombination in both somatic and meiotic cells in Arabidopsis

The human hereditary disease Fanconi anemia leads to severe symptoms, including developmental defects and breakdown of the hematopoietic system. It is caused by single mutations in the FANC genes, one of which encodes the DNA translocase FANCM (for Fanconi anemia complementation group M), which is required for the repair of DNA interstrand cross-links to ensure replication progression. We identified a homolog of FANCM in Arabidopsis thaliana that is not directly involved in the repair of DNA lesions but suppresses spontaneous somatic homologous recombination via a RecQ helicase (At-RECQ4A)-independent pathway. In addition, it is required for double-strand break-induced homologous recombination. The fertility of At-fancm mutant plants is compromised. Evidence suggests that during meiosis At-FANCM acts as antirecombinase to suppress ectopic recombination-dependent chromosome interactions, but this activity is antagonized by the ZMM pathway to enable the formation of interference-sensitive crossovers and chromosome synapsis. Surprisingly, mutation of At-FANCM overcomes the sterility phenotype of an At-MutS homolog4 mutant by apparently rescuing a proportion of crossover-designated recombination intermediates via a route that is likely At-MMS and UV sensitive81 dependent. However, this is insufficient to ensure the formation of an obligate crossover. Thus, At-FANCM is not only a safeguard for genome stability in somatic cells but is an important factor in the control of meiotic crossover formation.     

PROTON GRADIENT REGULATION5 Is Essential for Proper Acclimation of Arabidopsis Photosystem I to Naturally and Artificially Fluctuating Light Conditions

In nature, plants are challenged by constantly changing light conditions. To reveal the molecular mechanisms behind acclimation to sometimes drastic and frequent changes in light intensity, we grew Arabidopsis thaliana under fluctuating light conditions, in which the low light periods were repeatedly interrupted with high light peaks. Such conditions had only marginal effect on photosystem II but induced damage to photosystem I (PSI), the damage being most severe during the early developmental stages. We showed that PROTON GRADIENT REGULATION5 (PGR5)-dependent regulation of electron transfer and proton motive force is crucial for protection of PSI against photodamage, which occurred particularly during the high light phases of fluctuating light cycles. Contrary to PGR5, the NAD(P)H dehydrogenase complex, which mediates cyclic electron flow around PSI, did not contribute to acclimation of the photosynthetic apparatus, particularly PSI, to rapidly changing light intensities. Likewise, the Arabidopsis pgr5 mutant exhibited a significantly higher mortality rate compared with the wild type under outdoor field conditions. This shows not only that regulation of PSI under natural growth conditions is crucial but also the importance of PGR5 in PSI protection.     

Biomarkers of dementia: comparison of electrochemiluminescence results and reference ranges with conventional ELISA

We compared the performance of the Meso Scale Diagnostics electrochemiluminescence (MSD) multiplex assay for t-tau and p-tau(231), originally developed for measurement of brain cell extract and tissue cultures, with the established standard method, the Innogenetics ELISA for total and p-tau(181). The methods were also clinically evaluated with 120 samples from our mono center population. The established Innogenetics ELISA procedures have been well optimized to measure patient samples in the normal and pathological range. Compared to the MSD they were superior in the limit of detection for total as well as p-tau. The obtained reference values for our normal controls were in the upper third of the published studies. Innogenetics tau, Innogenetics p-tau(181) and MSD t-tau differentiated the Alzheimer's (n=44) and minimal impairment group (MCI, n=39) from normal controls (n=37), but the MCI group was not statistically different from the normal controls. The MSD multiplex assay measured t-tau adequately but p-tau(231) could not differentiate normal from pathological results in CSF due to the high limit of detection. Both procedures however, have to be further standardized and complemented by adequate internal and external quality control schemes to qualify for routine analysis in a medical laboratory.     

The inner-mitochondrial distribution of Oxa1 depends on the growth conditions and on the availability of substrates

The Oxa1 protein is a well-conserved integral protein of the inner membrane of mitochondria. It mediates the insertion of both mitochondrial- and nuclear-encoded proteins from the matrix into the inner membrane. We investigated the distribution of budding yeast Oxa1 between the two subdomains of the contiguous inner membrane--the cristae membrane (CM) and the inner boundary membrane (IBM)--under different physiological conditions. We found that under fermentable growth conditions, Oxa1 is enriched in the IBM, whereas under nonfermentable (respiratory) growth conditions, it is predominantly localized in the CM. The enrichment of Oxa1 in the CM requires mitochondrial translation; similarly, deletion of the ribosome-binding domain of Oxa1 prevents an enrichment of Oxa1 in the CM. The predominant localization in the IBM under fermentable growth conditions is prevented by inhibiting mitochondrial protein import. Furthermore, overexpression of the nuclear-encoded Oxa1 substrate Mdl1 shifts the distribution of Oxa1 toward the IBM. Apparently, the availability of nuclear- and mitochondrial-encoded substrates influences the inner-membrane distribution of Oxa1. Our findings show that the distribution of Oxa1 within the inner membrane is dynamic and adapts to different physiological needs.     

Online video-based resistance training improves the physical capacity of junior basketball athletes

ABSTRACT: Klusemann, MJ, Pyne, DB, Fay, T, and Drinkwater, EJ. Online Video-Based Resistance Training Improves the Physical Capacity of Junior Basketball Athletes. J Strength Cond Res 26(10): 2677-2684, 2012-Junior basketball athletes require a well-designed resistance training program to improve their physical development. Lack of expert supervision and resistance training in junior development pathways may be overcome by implementing an online video-based program. The aim of this study was to compare the magnitude of improvement (change) in physical performance and strength and functional movement patterns of junior basketball athletes using either a fully supervised or an online video-based resistance training program. Thirty-eight junior basketball athletes (males, n = 17; age, 14 ± 1 year; height, 1.79 ± 0.10 m; mass, 67 ± 12 kg; females, n = 21; age, 15 ± 1 year; height, 1.70 ± 0.07 m; mass, 62 ± 8 kg) were randomly assigned into a supervised resistance training group (SG, n = 13), video training group (VG, n = 13) or control group (CG, n = 12) and participated in a 6-week controlled experimental trial. Pre- and posttesting included measures of physical performance (20-m sprint, step-in vertical jump, agility, sit and reach, line drill, and Yo-Yo intermittent recovery level 1), strength (15 s push-up and pull-up), and functional movement screening (FMS). Both SG and VG achieved 3-5% ± 2-4% (mean ± 90% confidence limits) greater improvements in several physical performance measures (vertical jump height, 20-m sprint time, and Yo-Yo endurance performance) and a 28 ± 21% greater improvement in push-up strength compared with the CG. The SG attained substantially larger gains in FMS scores over both the VG (12 ± 10%) and CG (13 ± 8%). Video-based training appears to be a viable option to improve physical performance and strength in junior basketball athletes. Qualified supervision is recommended to improve functional movement patterns in junior athletes.     

Muscle activation strategies during strength training with heavy loading vs. repetitions to failure

Going to failure, or not, has probably been one of the most debated issues during the history of strength training. However, few studies have directly compared the physiological effect of failure vs. nonfailure strength training. The purpose of this study was to evaluate muscle activation strategies with electromyography (EMG) during heavy repetitions vs. repetitions to failure with lighter resistance. Fifteen healthy untrained women performed a set with heavy loading (3 repetition maximum [RM]) and a set of repetitions to failure with lower resistance (～15 RM) during lateral raise with elastic tubing. Electromyographic amplitude and median power frequency of specific shoulder and neck muscles were analyzed, and the BORG CR10 scale was used to rate perceived loading immediately after each set of exercise. During the failure set, normalized EMG was significantly lower during the first repetition and significantly higher during the latter repetitions compared with the heavy 3-RM set (p < 0.05). Normalized EMG for the examined muscles increased throughout the set to failure in a curvilinear fashion--e.g., for the trapezius from 86 to 124% maximal voluntary contraction (p < 0.001)--and reached a plateau during the final 3-5 repetitions before failure. Median power frequency for all examined muscles decreased throughout the set to failure in a linear fashion, indicating progressively increasing fatigue. In conclusion, going to complete failure during lateral raise is not necessary to recruit the entire motor unit pool in untrained women--i.e., muscle activity reached a plateau 3-5 repetitions from failure with an elastic resistance of approximately 15 RM. Furthermore, strengthening exercises performed with elastic tubing seem to be an efficient resistance exercise and a feasible and practical alternative to traditional resistance equipment.     

Prime-boost vaccination with rBCG/rAd35 enhances CD8⁺ cytolytic T-cell responses in lesions from Mycobacterium tuberculosis-infected primates

To prevent the global spread of tuberculosis (TB) infection, a novel vaccine that triggers potent and long-lived immunity is urgently required. A plasmid-based vaccine has been developed to enhance activation of major histocompatibility complex (MHC) class I–restricted CD8+ cytolytic T cells using a recombinant Bacille Calmette-Guérin (rBCG) expressing a pore-forming toxin and the Mycobacterium tuberculosis (Mtb) antigens Ag85A, 85B and TB10.4 followed by a booster with a nonreplicating adenovirus 35 (rAd35) vaccine vector encoding the same Mtb antigens. Here, the capacity of the rBCG/rAd35 vaccine to induce protective and biologically relevant CD8⁺ T-cell responses in a nonhuman primate model of TB was investigated. After prime/boost immunizations and challenge with virulent Mtb in rhesus macaques, quantification of immune responses at the single-cell level in cryopreserved tissue specimen from infected organs was performed using in situ computerized image analysis as a technological platform. Significantly elevated levels of CD3⁺ and CD8⁺ T cells as well as cells expressing interleukin (IL)-7, perforin and granulysin were found in TB lung lesions and spleen from rBCG/rAd35-vaccinated animals compared with BCG/rAd35-vaccinated or unvaccinated animals. The local increase in CD8⁺ cytolytic T cells correlated with reduced expression of the Mtb antigen MPT64 and also with prolonged survival after the challenge. Our observations suggest that a protective immune response in rBCG/rAd35-vaccinated nonhuman primates was associated with enhanced MHC class I antigen presentation and activation of CD8+ effector T-cell responses at the local site of infection in Mtb-challenged animals.