A new mutation in MT-ND1 m.3928G>C p.V208L causes Leigh disease with infantile spasms

New mutations in mitochondrial DNA encoded genes of complex I are rarely reported. An infant developed Leigh disease with infantile spasms. Complex I enzyme activity was deficient and response to increasing coenzyme Q concentrations was reduced. Complex I assembly was intact. A new mutation in MT-ND1 m.3928G>C p.V208L, affecting a conserved amino acid in a critical domain, part of the coenzyme Q binding pocket, was present at high heteroplasmy. The unaffected mother did not carry measurable mutant mitochondrial DNA, but concern remained for gonadal mosaicism. Prenatal testing was possible for a subsequent sibling. The ND1 p.V208L mutation causes Leigh disease.     

Histological and Micro-CT Evidence of Stigmatic Rostellum Receptivity Promoting Auto-Pollination in the Madagascan Orchid Bulbophyllum bicoloratum

Background

The rostellum, a projecting part of the gynostemium in orchid flowers, separates the anther(s) from the stigma and thus commonly prevents auto-pollination. Nonetheless, as a modified (usually distal) portion of the median stigma lobe, the rostellum has been frequently invoked of having re-gained a stigmatic function in rare cases of orchid auto-pollination. Here it is shown that a newly discovered selfing variant of Madagascan Bulbophyllum bicoloratum has evolved a modified rostellum allowing the penetration of pollen tubes from in situ pollinia.

Methods

Gynostemium micro-morphology and anatomy of selfing and outcrossing variants of B . bicoloratum was studied by using light and scanning electron microscopy and histological sections. Pollen tube growth in the selfing variant was further observed via X-ray computed microtomography (micro-CT), providing 3D reconstructions of floral tissues at a micron scale.

Findings

Selfing variants possess a suberect (‘displaced’) rostellum rather than the conventional, erect type. Very early in anthesis, the pollinia of selfers are released from the anther and slide down onto the suberect rostellum, where pollen tube growth preferentially occurs through the non-vascularized, i.e. rear (adaxial) and (semi-) lateral parts. This penetrated tissue is comprised of a thin layer of elongate and loosely arranged cells, embedded in stigmatic exudates, as also observed in the stigmatic cavity of both selfing and outcrossing variants.

Conclusions

Our results provide the first solid evidence of a stigmatic function for the rostellum in orchid flowers, thereby demonstrating for the first time the feasibility of the micro-CT technique for accurately visualizing pollen tube growth in flowering plants. Rostellum receptivity in B . bicoloratum probably uniquely evolved as an adaptation for reproductive assurance from an outcrossing ancestor possessing an erect (non-receptive) rostellum. These findings open up new avenues in the investigation of an organ that apparently re-gained its ‘primordial function’ of being penetrated by pollen tubes.     

Discovery of novel inhibitors targeting the Mycobacterium tuberculosis O-acetylserine sulfhydrylase (CysK1) using virtual high-throughput screening

Cysteine biosynthesis in Mycobacterium tuberculosis (MTB) is crucial for this pathogen to combat oxidative stress and for long term survival in the host. Hence inhibition of this pathway is attractive for developing novel drugs against tuberculosis. In the present study, the crystal structure of the mycobacterial enzyme O-acetylserine sulfhydrylase CysK1 bound to an oligopeptide inhibitor was used as a framework for virtual screening of the BITS-Pilani in-house database to identify new scaffolds as CysK1 inhibitors. Thirty compounds were synthesized and evaluated in vitro for their ability to inhibit CysK1, activity against M. tuberculosis and cytotoxicity as steps towards the derivation of structure–activity relationships (SAR) and lead optimization. Compound 8-nitro-4-(2-(trifluoromethyl)phenyl)-4,4a-dihydro-2H-pyrimido[5,4-e]thiazolo[3,2-a]pyrimidine-2,5(3H)-dione (4n) emerged as the most promising lead with an IC₅₀ of 17.7 μM for purified CysK1 and MIC of 7.6 μM for M. tuberculosis, with little or no cytotoxicity (>50 μM).     

Susceptibility to the Cry1F toxin of field populations of Sesamia nonagrioides (Lepidoptera: Noctuidae) in Mediterranean maize cultivation regions

Maize hybrids expressing the Cry1F toxin provide efficient control of lepidopteran pests. The Mediterranean corn borer, Sesamia nonagrioides (Lefèvre), is one of the most damaging pests of maize in the Mediterranean basin. In this work we firstly determined the efficacy of maize hybrids expressing the Cry1F toxin (event TC1507) to control neonates of S. nonagrioides. Leaf tissue feeding bioassays revealed that TC1507 maize is highly effective against this pest, and the percentage mortality obtained was comparable to that obtained with a Cry1Ab-expressing maize hybrid (Compa CB, event 176), which is known to be highly efficacious against S. nonagrioides. Secondly, interpopulation variation in the susceptibility to the Cry1F insecticidal protein was established for nine field-collected populations of S. nonagrioides (three Spanish, two French, two Italian, one Greek, and one Turkish). Estimates of the susceptibility of larvae to the Cry1F toxin showed low variability in lethal concentrations and growth inhibition concentrations among field populations. Moreover, no significant differences were found when they were grouped by geographical areas [Western Mediterranean (Spain and France) versus Eastern Mediterranean (Italy, Greece and Turkey)] or by history of exposure to Bt plants (Spanish vs. other populations). Therefore, the minor differences found in field populations can be attributed to natural variation in sensitivity to Cry1F. The importance of establishing baselines of susceptibility for resistance detection is discussed. Future changes in susceptibility of S. nonagrioides populations to Cry1F could be documented based on this baseline data.     

Distinguishing Neurocognitive Processes Reflected by P600 Effects: Evidence from ERPs and Neural Oscillations

Research on language comprehension using event-related potentials (ERPs) reported distinct ERP components reliably related to the processing of semantic (N400) and syntactic information (P600). Recent ERP studies have challenged this well-defined distinction by showing P600 effects for semantic and pragmatic anomalies. So far, it is still unresolved whether the P600 reflects specific or rather common processes. The present study addresses this question by investigating ERPs in response to a syntactic and pragmatic (irony) manipulation, as well as a combined syntactic and pragmatic manipulation. For the syntactic condition, a morphosyntactic violation was applied, whereas for the pragmatic condition, such as “That is rich”, either an ironic or literal interpretation was achieved, depending on the prior context. The ERPs at the critical word showed a LAN-P600 pattern for syntactically incorrect sentences relative to correct ones. For ironic compared to literal sentences, ERPs showed a P200 effect followed by a P600 component. In comparison of the syntax-related P600 to the irony-related P600, distributional differences were found. Moreover, for the P600 time window (i.e., 500–900 ms), different changes in theta power between the syntax and pragmatics effects were found, suggesting that different patterns of neural activity contributed to each respective effect. Thus, both late positivities seem to be differently sensitive to these two types of linguistic information, and might reflect distinct neurocognitive processes, such as reanalysis of the sentence structure versus pragmatic reanalysis.     

Electrical Vestibular Stimuli to Enhance Vestibulo-Motor Output and Improve Subject Comfort

Electrical vestibular stimulation is often used to assess vestibulo-motor and postural responses in both clinical and research settings. Stochastic vestibular stimulation (SVS) is a recently established technique with many advantages over its square-wave counterpart; however, the evoked muscle responses remain relatively small. Although the vestibular-evoked responses can be enhanced by increasing the stimulus amplitude, subjects often perceive these higher intensity electrical stimuli as noxious or painful. Here, we developed multisine vestibular stimulation (MVS) signals that include precise frequency contributions to increase signal-to-noise ratios (SNR) of stimulus-evoked muscle and motor responses. Subjects were exposed to three different MVS stimuli to establish that: 1) MVS signals evoke equivalent vestibulo-motor responses compared to SVS while improving subject comfort and reducing experimentation time, 2) stimulus-evoked vestibulo-motor responses are reliably estimated as a linear system and 3) specific components of the cumulant density time domain vestibulo-motor responses can be targeted by controlling the frequency content of the input stimulus. Our results revealed that in comparison to SVS, MVS signals increased the SNR 3–6 times, reduced the minimum experimentation time by 85% and improved subjective measures of comfort by 20–80%. Vestibulo-motor responses measured using both EMG and force were not substantially affected by nonlinear distortions. In addition, by limiting the contribution of high frequencies within the MVS input stimulus, the magnitude of the medium latency time domain motor output response was increased by 58%. These results demonstrate that MVS stimuli can be designed to target and enhance vestibulo-motor output responses while simultaneously improving subject comfort, which should prove beneficial for both research and clinical applications.     

Aryl Hetaryl Ketones and Thioketones as Efficient Inhibitors of Peptidyl‐Prolyl cis‐trans Isomerases

A series of 18 differently substituted new aryl hetaryl ketones and thioketones were synthesized in four to six steps from commercial starting materials. The new ketones were evaluated as inhibitors of the peptidyl‐prolyl cis‐trans isomerase hPin1 with K_i values ranging in the one‐digit micromolar to sub‐micromolar numbers. A crystal structure revealed the non‐planar arrangement of the aryl residues at the carbonyl compound and supports the hypothesis that the new compounds might mimic the transition state of the enzymatic conversion.