Performance Deficits in a Voluntary Saccade Task in Chinese “Express Saccade Makers”

Differences in behaviour and cognition have been observed in different human populations. It has been reported that in various types of complex visual task, eye movement patterns differ systematically between Chinese and non-Chinese participants, an observation that has been related to differences in culture between groups. However, we confirm here that, in healthy, naïve adult Chinese participants, a far higher proportion (22%) than expected (1–5%) exhibit a pattern of reflexive eye movement behaviour (high numbers of low latency express saccades) in circumstances designed to inhibit such responses (prosaccade overlap tasks). These participants are defined as “express saccade makers” (ESMs). We then show using the antisaccade paradigm, which requires the inhibition of reflexive responses and the programming and execution of voluntary saccades, that the performance of ESMs is compromised; they have higher antisaccade directional error rates, and the latency distributions of their error saccades again exhibit a higher proportion of low latency express saccade errors consistent with a reduced ability to inhibit reflexive responses. These results are difficult to reconcile with a cultural explanation as they relate to important and specific performance differences within a particular population. They suggest a potential unexpected confound relevant to those studies of Chinese versus other groups which have investigated group differences using oculomotor measures, and explained them in terms of culture. The confirmation of higher numbers of ESMs among Chinese participants provides new opportunities for examining oculomotor control.     

Effects of Turn Stability and Side-Chain Hydrophobicity on the Folding of β-Structures

Key elements of β-structure folding include hydrophobic core collapse, turn formation, and assembly of backbone hydrogen bonds. In the present folding simulations of several β-hairpins and β-sheets (peptide 1, protein G B1 domain peptide, TRPZIP2, TRPZIP4, 20mer, and 20mer^DP6D), the folding free-energy landscape as a function of several reaction coordinates corresponding to the three key elements indicates apparent dependence on turn stability and side-chain hydrophobicity, which demonstrates different folding mechanisms of similar β-structures of varied sequences. Turn stability is found to be the key factor in determining the formation order of the three structural elements in the folding of β-structures. Moreover, turn stability and side-chain hydrophobicity both affect the stability of backbone hydrogen bonds. The three-stranded β-sheets fold through a three-state transition in which the formation of one hairpin always takes precedence over the other. The different stabilities of two anti-parallel hairpins in each three-stranded β-sheet are shown to correlate well with the different levels of their hydrophobic interactions.     

Erratum to: “Effects of Different Conservation Methods on the Genetic Stability of Potato Germplasm”

Russian Journal of Plant Physiology -     

Effects of Dichloroethene Isomers on the Induction and Activity of Butane Monooxygenase in the Alkane-Oxidizing Bacterium “Pseudomonas butanovora”

We examined cooxidation of three different dichloroethenes (1,1-DCE, 1,2-trans DCE, and 1,2-cis DCE) by butane monooxygenase (BMO) in the butane-utilizing bacterium “Pseudomonas butanovora.” Different organic acids were tested as exogenous reductant sources for this process. In addition, we determined if DCEs could serve as surrogate inducers of BMO gene expression. Lactic acid supported greater rates of oxidation of the three DCEs than the other organic acids tested. The impacts of lactic acid-supported DCE oxidation on BMO activity differed among the isomers. In intact cells, 50% of BMO activity was irreversibly lost after consumption of ~20 nmol mg protein⁻¹ of 1,1-DCE and 1,2-trans DCE in 0.5 and 5 min, respectively. In contrast, a comparable loss of activity required the oxidation of 120 nmol 1,2-cis DCE mg protein⁻¹. Oxidation of similar amounts of each DCE isomer (~20 nmol mg protein⁻¹) produced different negative effects on lactic acid-dependent respiration. Despite 1,1-DCE being consumed 10 times faster than 1,2,-trans DCE, respiration declined at similar rates, suggesting that the product(s) of oxidation of 1,2-trans DCE was more toxic to respiration than 1,1-DCE. Lactate-grown “P. butanovora” did not express BMO activity but gained activity after exposure to butane, ethene, 1,2-cis DCE, or 1,2-trans DCE. The products of BMO activity, ethene oxide and 1-butanol, induced lacZ in a reporter strain containing lacZ fused to the BMO promoter, whereas butane, ethene, and 1,2-cis DCE did not. 1,2-trans DCE was unique among the BMO substrates tested in its ability to induce lacZ expression.     

Effect of pH and Glucose on the Stability of α-lactalbumin

The objective of this study is to understand the influence of pH and effect of cosolvent (glucose) on the stabilization of bovine α-lactalbumin by using ultrasonic techniques. Values of density, ultrasonic velocity and viscosity were measured for bovine α-lactalbumin (5 mg/ml) dissolved in phosphate buffer (pH 2, 5, 7, 9 and 12) solutions mixed with and without the cosolvent at 30 °C. These measurements were used to calculate few thermo-acoustical parameters such as adiabatic compressibility, intermolecular free length, acoustic impedance, relaxation time, relative association constant, the partial apparent specific volume and the partial apparent specific adiabatic compressibility for the said systems. The obtained results revealed a strong comparison between the effects of acidic and alkaline pH values on protein denaturation, i.e., the acidic pH are instantaneous and are of less magnitude whereas alkaline pH are slower but sharper. Further the present study supports the fact that the presence of glucose stabilizes α-lactalbumin against denaturation due to pH variation, which may be due to the strengthening of non-covalent interactions and the steric exclusion effect.     

Effects of Peptide and Non-Peptide Opioids on Protective Reaction of the Cockroach Periplaneta americana in the “Hot Camera”

The ability of morphine, naloxone, and several opioid peptides of the group of beta-casomorphines to change the time of the stay of cockroaches Periplaneta americana in a hot camera (t = 47°C) was studied. It has been shown that the morphine dose ED₅₀ increasing twice the stay amounts to 200 µg/g, while hat of naloxone, to 40, of heptapeptide YPFPGPI, to 440, and of pentapeptide YPFPG, to 420 µg/g. Hexapeptide YPFPGP free of the N-terminal tyrosine had no statistically significant effect on the stay duration. The earlier changes of the stay duration (in 15–60 min after injection; the most pronounced for morphine and naloxone) corresponded to the ability of these drugs to act on the mu-type opioid receptors. The high peptide affinity to the delta-type receptors led to development of the later effects (in 90–150 min after injection; the most pronounced for heptapeptide YPFPGPI). A combined injection of naloxone and heptapeptide lead to the mutual inhibition of their effect: the peptide eliminated the early effect of naloxone on the stay duration, whereas naloxone, the late effects of beta-casomorphine. The obtained results indicate an important role of the endogenous opioid system in control of protective behavior of insects, as well as heterogeneity of the receptor components of the system.     

Effects of the Chaperone Inducer U133 on Sleep–Wake Cycle Temporal Characteristics and Spatial Memory

Journal of Evolutionary Biochemistry and Physiology - U133, a chaperone inducer synthesized on the basis of echinochrome A, has antitumor, antioxidant and neuroprotective activity. The breadth of...     

Effects of Experimental Choices and Analysis Noise on Surveys of the “Rare Biosphere”

When planning a survey of 16S rRNA genes from a complex environment, investigators face many choices including which primers to use and how to taxonomically classify sequences. In this study, we explored how these choices affected a survey of microbial diversity in a sample taken from the aerobic basin of the activated sludge of a North Carolina wastewater treatment plant. We performed pyrosequencing reactions on PCR products generated from primers targeting the V1-V2, V6, and V6-V7 variable regions of the 16S rRNA gene. We compared these sequences to 16S rRNA gene sequences found in a whole-genome shotgun pyrosequencing run performed on the same sample. We found that sequences generated from primers targeting the V1-V2 variable region had the best match to the whole-genome shotgun reaction across a range of taxonomic classifications from phylum to family. Pronounced differences between primer sets, however, occurred in the “rare biosphere” involving taxa that we observed in fewer than 11 sequences. We also examined the results of analysis strategies comparing a classification scheme using a nearest-neighbor approach to directly classifying sequences with a naïve Bayesian algorithm. Again, we observed pronounced differences between these analysis schemes in infrequently observed taxa. We conclude that if a study is meant to probe the rare biosphere, both the experimental conditions and analysis choices will have a profound impact on the observed results.For nearly 3 decades, investigations of the distribution of microbes in complex environments have focused on the use of rRNA genes (1, 2, 4, 11, 16, 18, 19, 22, 24). Because the full-length 16S rRNA sequence can be obtained with paired-end reads via traditional Sanger sequencing, until recently most studies of the 16S rRNA gene captured most or nearly most of the 16S sequence length. New pyrosequencing technologies, however, have recently been introduced that greatly reduce the per base cost of sequencing but with shorter read lengths than traditional Sanger sequencing (17). This new approach has proven powerful, yielding a previously unobtainable view of rare taxa (7, 12-14, 25).The shorter reads produced by pyrosequencing require the choice of a particular region of the 16S rRNA gene to target for pyrosequencing as well as the choice of an algorithm to classify the taxonomy of the shorter reads. In their initial surveys of microbial diversity with pyrosequencing (12, 14, 25), Sogin and colleagues targeted the V6 variable region, in part because it is was small enough to be captured with the 100-bp reads of the pyrosequencing technology available at the time. Recently, the read length of 454 pyrosequencing machines has been increased to an average of ∼250 bp. This allows for more flexibility in primer design and opens up the possibility of targeting regions of the 16S rRNA gene other than V6. In recent work, Huse et al. took advantage of this new capability to compare the classifications made for the human gut microbiome with the V6 and longer V3 regions (13). Plotting the taxonomic abundance of these two sequence sets against each other yielded an excellent correlation (r² = 0.99), suggesting that the choice of which variable region to target makes little difference. In this report, we introduce a data set examining the performance of sets of primers targeting the V1-V2, V6, and V6-V7 regions. By using a sample for which we have also generated a whole-genome shotgun sequencing run with 250 bp reads, we were able to compare the observed 16S rRNA genes in samples with and without an initial PCR step targeting the 16S rRNA gene. Our results demonstrate that experimental choices such as which region of the 16S rRNA gene to sequence and which algorithm to use to classify taxa are much more likely to affect observations of the “rare biosphere” than more commonly observed taxa.     

Effects of Aging and Idiopathic Parkinson’s Disease on Tactile Temporal Order Judgment

It is generally accepted that the basal ganglia play an important role in interval timing that requires the measurement of temporal durations. By contrast, it remains controversial whether the basal ganglia play an essential role in temporal order judgment (TOJ) of successive stimuli, a behavior that does not necessarily require the measurement of durations in time. To address this issue, we compared the effects of idiopathic Parkinson’s disease (PD) on the TOJ of two successive taps delivered to each hand, with the arms uncrossed in one condition and crossed in another. In addition to age-matched elderly participants without PD (non-PD), we examined young healthy participants so that the effect of aging could serve as a control for evaluating the effects of PD. There was no significant difference between PD and non-PD participants in any parameter of TOJ under either arm posture, although reaction time was significantly longer in PD compared with non-PD participants. By contrast, the effect of aging was apparent in both conditions. With their arms uncrossed, the temporal resolution (the interstimulus interval that yielded 84% correct responses) in elderly participants was significantly worse compared with young participants. With their arms crossed, elderly participants made more errors at longer intervals (~1 s) than young participants, although both age groups showed similar judgment reversal at moderately short intervals (~200 ms). These results indicate that the basal ganglia and dopaminergic systems do not play essential roles in tactile TOJ involving both hands and that the effect of aging on TOJ is mostly independent of the dopaminergic systems.     

Temporal regulation in the synthesis of concanavalin a and α-mannosidase in the seeds of Canavalia ensiformis

The enzyme,α-mannosidase and the lectin, concanavalin A, both of which interact with α-D-mannosides, are present in substantial amounts in the mature seeds of Canavalia ensiformis. The changes in the levels of these two proteins and their mRNA have been followed throughout seed development. Although both proteins start appearing in the seeds at day 24 after pod formation, there is a difference in the developmental patterns. While the increase in the activity of α-mannosidase is gradual and continues up until about day 44 followed by a slow phase till the desiccation stage, Con A after a lag phase which lasts to about day 30 shows a logarithmic increase up to about the 36th day followed by a plateau thereafter upto the desiccation stage. The highest amounts of functional mRNA for these two proteins are found at the early stages of seed development, well ahead of the period of highest protein deposition, thereby indicating that post-translational modifications of these proteins are slow and distinct from those of other legumes.     

Effects of low-dose γ-rays on the embryonic development of mouse melanoblasts and melanocytes in the epidermis and hair bulbs

The effects of low-dose γ-rays on the embryonic development of animal cells are not well studied. The mouse melanocyte is a good model to study the effects of low-dose γ-rays on the development of animal cells, as it possesses visible pigment (melanin) as a differentiation marker. The aim of this study is to investigate in detail the effects of low-dose γ-rays on embryonic development of mouse melanoblasts and melanocytes in the epidermis and hair bulbs at cellular level. Pregnant females of C57BL/10J mice at nine days of gestation were whole-body irradiated with a single acute dose of γrays (0.1, 0.25, 0.5, and 0.75 Gy), and the effects of γ-rays were studied by scoring changes in the development of epidermal melanoblasts and melanocytes, hair follicles, and hair bulb melanocytes at 18 days in gestation. The number of epidermal melanoblasts and melanocytes, hair follicles, and hair bulb melanocytes in the dorsal and ventral skins was markedly decreased even at 0.1 Gy-treated embryos (P < 0.001), and gradually decreased as dose increased. The effects on the ventral skin were greater than those on the dorsal skin. The dramatic reduction in the number of melanocytes compared to melanoblasts was observed in the ventral skin, but not in the dorsal skin. These results suggest that low-dose γ-rays provoke the death of melanoblasts and melanocytes, or inhibit the proliferation and differentiation of melanoblasts and melanocytes, even at the low dose.     

Implication of C-Terminal Deletion on the Structure and Stability of Bovine β-casein

Bovine β-casein (β-CN) with its C-terminal truncated by chymosin digestion, β-CN-(f1-192), was examined and characterized using circular dichroism (CD) under various temperature conditions. CONTIN/LL analysis of the CD data revealed significant secondary structure disruption in β-CN-(f1-192) relative to its parent protein,β-CN, in the temperature range (5° to 70°C) studied. Near-UV CD spectra indicated significant temperature dependent structural changes. Analytical ultracentrifugation results showed significant reduction but not complete abolishment of self-association in β-CN-(f1-192) compared to whole β-casein at 2°–37°C. Furthermore, binding experiments with the common hydrophobic probe – 8-anilino-1- naphthalene sulfonic acid (ANS) illustrated that β-CN-(f1-192) is nearly incapable of binding to ANS relative to whole β-CN, suggesting a nearly complete open overall tertiary structure brought about by the C-terminal truncation. It has been demonstrated clearly that the tail peptide β-CN-(f193-209) is important in maintaining the hydrophobic core of β-CN but the residual association observed argues for a minor role for other sites as well.     

Effects of “skeleton” photoperiods and high frequency light-dark cycles on the rhythm of cell division in synchronized cultures of Euglena

Summary Two further lines of evidence support the contention (Edmunds, 1966) that the cell cycle in autotrophically grown Euglena can be coupled to an endogenous, circadian biological clock under certain conditions. So-called skeleton photoperiods (LD: 3,6,3:12 and LD: 4,4,4:12) following a complete photoperiod regime entrain the cell division rhythm in the population to a precise 24 hr period, although the step-sizes of the successive fission bursts are always less than 2.00, indicating that not all cells divide in any one 24 hr interval. These findings imply that the continuous action of light is not required for synchronization and suggest that the putative oscillation underlying the rhythm can be phased by discrete light (or dark) pulses or signals.The effects of high frequency LD cycles whose periods were integral submultiples of 24 hr were also investigated. In most regimes (LD:1/4,1/2; LD:1/2,1; LD: 1,2; LD: 1,3; LD: 2,4; LD: 2,6; LD: 4,4) synchronous cell division iccurred in the culture with an average period of 26–27 hr, although only a fraction of the cells divided during any one burst. Similar results were obtained if (i) a synchronized culture was exposed to certain high frequency cycles whose periods were not integral submultiples of 24 hr (e.g., LD: 5,5 or LD: 8,8); (ii) an asynchronous culture (grown in LL) was subsequently exposed to a high frequency cycle; or (iii) a synchronized culture was subjected to a random LD cycle. The synchrony does not break down as long as the given LD regime is imposed and shows some indications of persistence in certain ensuing conditions of continuous illumination.A general formula was derived which predicts the time of division, t _D , for an individual cell: t _D =k+n, where k is the initial phase delay, n is an integer, and is the free-running period of the rhythm observed in the population. These results are interpreted as indicating that the high frequency cycles employed were unable to entrain the circadian oscillation(s) hypothesized to underly and gate cell division, with the result that the rhythm reverted to its free-running period. Exposure to such cycles, however, apparently either initiates a rhythm or synchronizes the phases of the individual oscillations in the populations of cells. The possible direct interaction between energy supply and the observed somewhat variable period lengths is discussed; also, the relevance of stochastic models for the decay of division synchrony in the absence of a recurrent synchronizing procedure is considered.Some of these results were initially reported at the 5th International Congress on Photobiology, Hanover, N.H., U.S.A., August 26–31, 1968.This work was supported by NSF research grants #GB-4140 and #GB-6892 to L. Edmunds.     

Effects of indomethacin and prostaglandin F2α on ovulation and ovarian contractility in the rabbit

The present investigation was carried out to determine whether inhibition of ovulation in the rabbit by administration of indomethacin can be correlated with any change in ovarian contractility at ovulation time and can be reversed by administration of prostaglandins. Indomethacin was adminstered intra-muscularly using three different schedules in a dose of 5 mg/kg. A reduced number of ruptured follicles following HCG was noted in all groups treated with indomethacin. Infusion of PGF_2α into the aorta (1 μg/kg/min.) could reverse this effect. Less pronounced ovarian contractility was observed after indomethacin treatment, but infusion of PGF_2α immediately enhanced contractility in ovaries from indomethacin treated rabbits. The inhibition of ovulation in the rabbit associated with indomethacin adminstration may be related to suppression of ovarian contractions. These data also suggest that prostaglandins may play a significant role in the mechanism of ovulation through an influence on ovarian contractility.     

Effect of Glycosylation on the Catalytic and Conformational Stability of Homologous α-Amylases

summary. A thermostable -amylase from B. licheniformis (BLA) and a mesophilic amylase from B. amyloliquefaciens (BAA) were covalently coupled to oxidized synthetic sucrose polymers (OSP400 and OSP70) and polyglutaraldehyde (PGA) by reductive alkylation to study the effect of neoglycosylation on the activity, kinetic and thermodynamic stability. The catalytic efficiency of the modified enzymes was comparable to that of the native enzyme. Covalent coupling decreased the rate of inactivation at all the temperatures studied, both in the presence and absence of added Ca²⁺. The stability of the native enzyme was found to increase upon modification as observed from the increase in t_1/2 in the absence of Ca²⁺ ions by about 1.5–13.7 times (at 85°C) in the case of BLA and 5.7–8.4 times (at 50°C) for BAA. The highest stability was observed for OSP400 modified enzyme with C_m and T_m values of 0.63 M and 7.92°C for BLA and 0.85 M and 5.3°C for BAA, respectively. The order of stability was OSP400 > OSP70 > PGA > Native for both BLA and BAA. The stability of the modified amylases obtained from the present study were superior compared to most of the single and double mutants obtained by site-directed mutagenesis that were constructed so as to enhance the intrinsic stability of these enzymes.This article is dedicated to Dr. P.V. Sundaram.     

Effects of 17β-estradiol and bisphenol A on the formation of reproductive organs in planarians

Planarians have a remarkable capacity for regeneration after ablation, and they reproduce asexually by fission. However, some planarians can also reproduce and maintain their sexual organs. During the regenerative process, their existing sexual organs degenerate and new ones develop. However, little is known about hormonal regulation during the development of reproductive organs in planarians. In this study, we investigated the effects of 17β-estradiol (a steroid) and bisphenol A (an endocrine disrupter) on the formation of sexual organs in the hermaphroditic planarian Dugesia ryukyuensis. Under control conditions, all worm tissues regenerated into sexual planarians with sexual organs within 4 weeks after ablation. However, in the presence of bisphenol A or 17β-estradiol, although they apparently regenerated into sexual planarians, the yolk glands, which are one of the female sexual organs, failed to regenerate even 7 weeks after ablation. These data suggest that planarians have a steroid hormone system, which plays a key role in the formation and maturation of sexual organs.     

Influence of Polyols on the Stability and Kinetic Parameters of Invertase from Candida utilis: Correlation with the Conformational Stability and Activity

Invertase (β-d-fructofuranoside fructohydrolase-E.C. 3.2.1.26) is a sucrose hydrolyzing enzyme found in microbial, plant and animal sources. Invertase from Candida utilis is a dimeric glycoprotein composed of two identical monomer subunits with an apparent molecular mass of 150 kDa. We investigated the mechanism of stabilization of invertase with polyols (glycerol, xylitol, and sorbitol). Activity, thermodynamic and kinetic measurements of invertase were performed as a function of polyol concentration and showed that polyols act as very effective stabilizing agents. The result from the solvent-invertase interaction shows preferential exclusion of the polyols from the protein domain leading to preferential hydration of protein. Apparent thermal denaturation temperature of the protein (T _m ) rose from 75 °C to a maximum of 85 °C in 30% glycerol. The stabilization has been attributed to the preferential hydration of the enzyme.