Covert Anti-Compensatory Quick Eye Movements during Head Impulses

Background

Catch-up saccades during passive head movements, which compensate for a deficient vestibulo-ocular reflex (VOR), are a well-known phenomenon. These quick eye movements are directed toward the target in the opposite direction of the head movement. Recently, quick eye movements in the direction of the head movement (covert anti-compensatory quick eye movements, CAQEM) were observed in older individuals. Here, we characterize these quick eye movements, their pathophysiology, and clinical relevance during head impulse testing (HIT).

Methods

Video head impulse test data from 266 patients of a tertiary vertigo center were retrospectively analyzed. Forty-three of these patients had been diagnosed with vestibular migraine, and 35 with Menière’s disease.

Results

CAQEM occurred in 38% of the patients. The mean CAQEM occurrence rate (per HIT trial) was 11±10% (mean±SD). Latency was 83±30 ms. CAQEM followed the saccade main sequence characteristics and were compensated by catch-up saccades in the opposite direction. Compensatory saccades did not lead to more false pathological clinical head impulse test assessments (specificity with CAQEM: 87%, and without: 85%). CAQEM on one side were associated with a lower VOR gain on the contralateral side (p<0.004) and helped distinguish Menière’s disease from vestibular migraine (p = 0.01).

Conclusion

CAQEM are a common phenomenon, most likely caused by a saccadic/quick phase mechanism due to gain asymmetries. They could help differentiate two of the most common causes of recurrent vertigo: vestibular migraine and Menière’s disease.     

Arabidopsis thaliana leaf-surface extracts are detected by the cabbage root fly (Delia radicum) and stimulate oviposition

Abstract. Oviposition of the cabbage root fly, Delia radicum (Diptera, Anthomyiidae) is stimulated by leaf‐surface extracts of Arabidopsis thaliana (L.) Heynh. (Brassicaceae) ecotype Columbia. The leaf surface of A. thaliana, similar to that of many other crucifers, contains glucosinolates and CIF (‘cabbage identification factor’; 1,2‐dehydro‐3‐thia‐4,10,10b‐triaza‐cyclopenta[.a.]fluorene‐1‐carboxylic acid). These compounds stimulate receptor neurones of the tarsal sensilla of D. radicum whereas additional, unknown compounds are detected by other receptor neurones.     

Arabidopsis cytochrome P450 monooxygenase 71A13 catalyzes the conversion of indole-3-acetaldoxime in camalexin synthesis

Camalexin (3-thiazol-2-yl-indole) is an indole alkaloid phytoalexin produced by Arabidopsis thaliana that is thought to be important for resistance to necrotrophic fungal pathogens, such as Alternaria brassicicola and Botrytis cinerea. It is produced from Trp, which is converted to indole acetaldoxime (IAOx) by the action of cytochrome P450 monooxygenases CYP79B2 and CYP79B3. The remaining biosynthetic steps are unknown except for the last step, which is conversion of dihydrocamalexic acid to camalexin by CYP71B15 (PAD3). This article reports characterization of CYP71A13. Plants carrying cyp71A13 mutations produce greatly reduced amounts of camalexin after infection by Pseudomonas syringae or A. brassicicola and are susceptible to A. brassicicola, as are pad3 and cyp79B2 cyp79B3 mutants. Expression levels of CYP71A13 and PAD3 are coregulated. CYP71A13 expressed in Escherichia coli converted IAOx to indole-3-acetonitrile (IAN). Expression of CYP79B2 and CYP71A13 in Nicotiana benthamiana resulted in conversion of Trp to IAN. Exogenously supplied IAN restored camalexin production in cyp71A13 mutant plants. Together, these results lead to the conclusion that CYP71A13 catalyzes the conversion of IAOx to IAN in camalexin synthesis and provide further support for the role of camalexin in resistance to A. brassicicola.     

Susceptibility of Anthonomus grandis (cotton boll weevil) and Spodoptera frugiperda (fall armyworm) to a cry1ia-type toxin from a Brazilian Bacillus thuringiensis strain

Different isolates of the soil bacterium Bacillus thuringiensis produce multiple crystal (Cry) proteins toxic to a variety of insects, nematodes and protozoans. These insecticidal Cry toxins are known to be active against specific insect orders, being harmless to mammals, birds, amphibians, and reptiles. Due to these characteristics, genes encoding several Cry toxins have been engineered in order to be expressed by a variety of crop plants to control insectpests. The cotton boll weevil, Anthonomus grandis, and the fall armyworm, Spodoptera frugiperda, are the major economically devastating pests of cotton crop in Brazil, causing severe losses, mainly due to their endophytic habit, which results in damages to the cotton boll and floral bud structures. A cry1Ia-type gene, designated cry1Ia12, was isolated and cloned from the Bt S811 strain. Nucleotide sequencing of the cry1Ia12 gene revealed an open reading frame of 2160 bp, encoding a protein of 719 amino acid residues in length, with a predicted molecular mass of 81 kDa. The amino acid sequence of Cry1Ia12 is 99% identical to the known Cry1Ia proteins and differs from them only in one or two amino acid residues positioned along the three domains involved in the insecticidal activity of the toxin. The recombinant Cry1Ia12 protein, corresponding to the cry1Ia12 gene expressed in Escherichia coli cells, showed moderate toxicity towards first instar larvae of both cotton boll weevil and fall armyworm. The highest concentration of the recombinant Cry1Ia12 tested to achieve the maximum toxicities against cotton boll weevil larvae and fall armyworm larvae were 230 microg/mL and 5 microg/mL, respectively. The herein demonstrated insecticidal activity of the recombinant Cry1Ia12 toxin against cotton boll weevil and fall armyworm larvae opens promising perspectives for the genetic engineering of cotton crop resistant to both these devastating pests in Brazil.     

Maize nitrilases have a dual role in auxin homeostasis and beta-cyanoalanine hydrolysis

The auxin indole-3-acetic acid (IAA), which is essential for plant growth and development, is suggested to be synthesized via several redundant pathways. In maize (Zea mays), the nitrilase ZmNIT2 is expressed in auxin-synthesizing tissues and efficiently hydrolyses indole-3-acetonitrile to IAA. Zmnit2 transposon insertion mutants were compromised in root growth in young seedlings and sensitivity to indole-3-acetonitrile, and accumulated lower quantities of IAA conjugates in kernels and root tips, suggesting a substantial contribution of ZmNIT2 to total IAA biosynthesis in maize. An additional enzymatic function, turnover of beta-cyanoalanine, is acquired when ZmNIT2 forms heteromers with the homologue ZmNIT1. In plants carrying an insertion mutation in either nitrilase gene this activity was strongly reduced. A dual role for ZmNIT2 in auxin biosynthesis and in cyanide detoxification as a heteromer with ZmNIT1 is therefore proposed.     

Processing of abstract rule violations in audition

The ability to encode rules and to detect rule-violating events outside the focus of attention is vital for adaptive behavior. Our brain recordings reveal that violations of abstract auditory rules are processed even when the sounds are unattended. When subjects performed a task related to the sounds but not to the rule, rule violations impaired task performance and activated a network involving supratemporal, parietal and frontal areas although none of the subjects acquired explicit knowledge of the rule or became aware of rule violations. When subjects tried to behaviorally detect rule violations, the brain's automatic violation detection facilitated intentional detection. This shows the brain's capacity for abstraction - an important cognitive function necessary to model the world. Our study provides the first evidence for the task-independence (i.e. automaticity) of this ability to encode abstract rules and for its immediate consequences for subsequent mental processes.     

NFU-Enabled FASTA: moving bioinformatics applications onto wide area networks

Background  

Advances in Internet technologies have allowed life science researchers to reach beyond the lab-centric research paradigm to create distributed collaborations. Of the existing technologies that support distributed collaborations, there are currently none that simultaneously support data storage and computation as a shared network resource, enabling computational burden to be wholly removed from participating clients. Software using computation-enable logistical networking components of the Internet Backplane Protocol provides a suitable means to accomplish these tasks. Here, we demonstrate software that enables this approach by distributing both the FASTA algorithm and appropriate data sets within the framework of a wide area network.     

Interfacial rheology of surface-active biopolymers: Acacia senegal gum versus hydrophobically modified starch

Acacia gum is a hybrid polyelectrolyte containing both protein and polysaccharide subunits. We study the interfacial rheology of its adsorption layers at the oil/water interface and compare it with adsorbed layers of hydrophobically modified starch, which for economic and political reasons is often used as a substitute for Acacia gum in technological applications. Both the shear and the dilatational rheological responses of the interfaces are considered. In dilatational experiments, the viscoelastic response of the starch derivative is just slightly weaker than that for Acacia gum, whereas we found pronounced differences in shear flow: The interfaces covered with the plant gum flow like a rigid, solidlike material with large storage moduli and a linear viscoelastic regime limited to small shear deformations, above which we observe apparent yielding behavior. In contrast, the films formed by hydrophobically modified starch are predominantly viscous, and the shear moduli are only weakly dependent on the deformation. Concerning their most important technological use as emulsion stabilizers, the dynamic interfacial responses imply not only distinct interfacial dynamics but also different stabilizing mechanisms for these two biopolymers.     

Oaths for physicians--necessary protection or elaborate hoax?

The ritual of taking an oath upon graduating from medical school is, with a few exceptions, a routine requirement for graduation. Albeit that many students believe that they have taken the Hippocratic Oath, this is virtually never the case. Very often students themselves write many of these oaths, and taking such an oath impresses the student as well as the public, who are potential patients. It sketches the ethically proper way for physicians to treat their patients. Such an oath is meaningful only when it is not coerced but in reality sketches the physicians' obligations toward patients, society, and each other. The question and problem of a coerced oath are discussed. It is concluded that students when first entering medical school know that such an oath will be a requirement for graduation, and because much of the time the persons taking the oath are writing it, I believe that coercion is not a factor. It is an unfortunate fact that throughout the nation students who are known to behave in ethically inappropriate ways are nevertheless allowed to graduate. Possible ways of addressing this troubling situation are discussed. Equally troublesome is the fact that we who administer the oath as well as the students who swear to it are aware that the system of medical care makes it extremely difficult and at times impossible to truly adhere to the full implications of this oath. According to the oath, physicians (in virtually all formulations) swear that social standing (and by implication economic factors) will not change the way in which patients are treated. This becomes impossible when uninsured patients are sent away at the front desk long before the physician can interact with them. Furthermore, the current fact that physicians often are confronted with not doing what they consider a necessary test (or prescribe what they think would be the best medication) raises the problem of either lying or suggesting to the patient that he/she do so--a fact that in the long run cannot help but damage the physician's veracity and the trust which patients put in their physicians. That virtually all codes of the American Medical Association (AMA) as well as the various specialties insist that physicians work toward universal access is stressed.