Species specificity in photoperiodic control of nymphal development in four species of cricket from north-west China

Photoperiodic regulation of nymphal development was examined in four species of cricket collected in the Xinjiang‐Uygur Autonomy Region, China (approximately 43°N, 81–89°E). Fifty percent of individuals of Modicogryllus frontalis reared at 28°C reached adulthood in approximately 80 days in conditions of 11 h light : 13 h dark (LD 11:13) to 14:10, and in approximately 95 days under LD 15:9 to 16:8. Melanogryllus desertus started adult emergence earliest under LD 16:8 at 28°C, but some individuals required much longer to mature, and thus two peaks of adult emergence occurred at approximately 60 and 160 days after hatching. More individuals hatched during the late peak in LD 18:6 than in LD 16:8. The mean nymphal period was approximately 100 days in LD 11:13 to 14:10. Both species showed short‐day type photoperiodic responses, but Mo. frontalis developed faster than did Me. desertus. The latter occupied a wider range of habitat conditions and was more variable in life cycle than the former. Modicogryllus burdigalensis started adult emergence earliest in LD 16:8 at 28°C in the six photoperiods tested, most adults emerging within 60 days. The mean nymphal period was 80 days in LD 15:9, 135 days in LD 14:10 and 80–100 days in LD 11:13 to 13:11, showing an intermediate type of photoperiodic response. Acheta domesticus was a long‐day type species, and the proportion of delayed individuals increased with decreasing photoperiod. In the dry climate of Xinjiang‐Uygur, nymphal overwintering seems to be successful in all of the four different patterns of nymphal development.     

Rabbit antibody detection with RNA aptamers

Antibody-based detection systems are widely used, but in the cases of immunoprecipitations and enzyme-linked immunoassays, they can be laborious. These techniques require the preparation of at least two kinds of non-cross-reactive immunoglobulin Gs (IgGs), usually made from different species against the single target molecule. Aptamers composed of nucleic acids possess strict recognition ability for the target molecule's three-dimensional structure and, thus, are considered to act like IgG. In this study, experimental trials were designed to combine the advantages of IgG and aptamers. For this purpose, aptamers against rabbit IgG were identified by in vitro selection. One of the obtained aptamers had a dissociation constant lower than 15 pM to the rabbit IgG. It bound specifically to the constant region of the rabbit IgG, and no binding was observed with mouse or goat IgG. Moreover, this aptamer recognized only the native form of rabbit IgG and could not bind the sodium dodecyl sulfate (SDS)-denatured form. These features show the advantage of using the aptamer as a secondary probing agent rather than the usual secondary antibodies.     

Effect of Glycine on Thiazole Biosynthesis in Escherichia coli

Glycine was found to replace thiamine thiazole for the growth of the thiazoleless mutant of Escherichia coli; it also stimulated the production of thiamine thiazole by washed cell suspensions of the mutant.     

Inhibition of aspartate aminotransferase by hydrazinosuccinate

DL-Hydrazinosuccinic acid was synthesized by the reaction of DL-bromosuccinic acid with hydrazine. The compound strongly inhibited aspartate aminotransferase and gave 50% inhibition at 1.3 μM when added simultaneously with L-aspartate to an assay mixture containing enzyme. Incubation of the enzyme with the compound prior to assay resulted in a much stronger inhibition, which proceeded time-dependently. The inhibition was protectable with L-aspartate and was substantially reversed by dialysis.     

Detection of Appearing and Disappearing Objects in Complex Acoustic Scenes

The ability to detect sudden changes in the environment is critical for survival. Hearing is hypothesized to play a major role in this process by serving as an “early warning device,” rapidly directing attention to new events. Here, we investigate listeners'' sensitivity to changes in complex acoustic scenes—what makes certain events “pop-out” and grab attention while others remain unnoticed? We use artificial “scenes” populated by multiple pure-tone components, each with a unique frequency and amplitude modulation rate. Importantly, these scenes lack semantic attributes, which may have confounded previous studies, thus allowing us to probe low-level processes involved in auditory change perception. Our results reveal a striking difference between “appear” and “disappear” events. Listeners are remarkably tuned to object appearance: change detection and identification performance are at ceiling; response times are short, with little effect of scene-size, suggesting a pop-out process. In contrast, listeners have difficulty detecting disappearing objects, even in small scenes: performance rapidly deteriorates with growing scene-size; response times are slow, and even when change is detected, the changed component is rarely successfully identified. We also measured change detection performance when a noise or silent gap was inserted at the time of change or when the scene was interrupted by a distractor that occurred at the time of change but did not mask any scene elements. Gaps adversely affected the processing of item appearance but not disappearance. However, distractors reduced both appearance and disappearance detection. Together, our results suggest a role for neural adaptation and sensitivity to transients in the process of auditory change detection, similar to what has been demonstrated for visual change detection. Importantly, listeners consistently performed better for item addition (relative to deletion) across all scene interruptions used, suggesting a robust perceptual representation of item appearance.     

K+/H+ antiporter in alkaliphilic Bacillus sp. no. 66 (JCM 9763)

A K⁺/H⁺ antiport system was detected for the first time in right-side-out membrane vesicles prepared from alkaliphilic Bacillus sp. no. 66 (JCM 9763). An outwardly directed K⁺ gradient (intravesicular K⁺ concentration, K_in, 100 mM; extravesicular K⁺ concentration, K_out, 0.25 mM) stimulated uphill H⁺ influx into right-side-out vesicles and created the inside-acidic pH gradient (ΔpH). This H⁺ influx was pH-dependent and increased as the pH increased from 6.8 to 8.4. Addition of 100 μM quinine inhibited the H⁺ influx by 75%. This exchange process was electroneutral, and the H⁺ influx was not stimulated by the imposition of the membrane potential (interior negative). Addition of K⁺ at the point of maximum ΔpH caused a rapid K⁺-dependent H⁺ eflux consistent with the inward exchange of external K⁺ for internal H⁺ by a K⁺/H⁺ antiporter. Rb⁺ and Cs⁺ could replace K⁺ but Na⁺ and Li⁺ could not. The H⁺ efflux rate was a hyperbolic function of K⁺ and increased with increasing extravesicular pH (pH_out) from 7.5 to 8.5. These findings were consistent with the presence of K⁺/H⁺ antiport activity in these membrane vesicles. Received: March 20, 1997 / Accepted: May 22, 1997     

Localization and functional analysis of the insect‐specific RabX4 in the brain of Bombyx mori

Rab proteins are small monomeric GTPases/GTP‐binding proteins, which form the largest branch of the Ras superfamily. The different Rab GTPases are localized to the cytosolic face of specific intracellular membranes, where they function as regulators of distinct steps in membrane trafficking. RabX4 is an insect‐specific Rab protein that has no close homolog in vertebrates. There is little information about insect‐specific Rab proteins. RabX4 was expressed in Escherichia coli and subsequently purified. Antibodies against Bombyx mori RabX4 were produced in rabbits for western immunoblotting and immunohistochemistry. Western blotting of neural tissues revealed a single band, at approximately 26 kD. RabX4‐like immunohistochemical reactivity was restricted to neurons of the pars intercerebralis and dorsolateral protocerebrum in the brain. Further immunohistochemical analysis revealed that RabX4 colocalized with Rab6 and bombyxin in the corpus allatum, a neuronal organ that secretes neuropeptides synthesized in the brain into the hemolymph. RabX4 expression in the frontal ganglion, part of the insect stomatogastric nervous system that is found in most insect orders, was restricted to two neurons on the outer region and did not colocalize with allatotropin or Rab6. Furthermore, RNA interference of RabX4 decreased bombyxin expression levels in the brain. These findings suggest that RabX4 is involved in the neurosecretion of a secretory organ in Bombyx mori.     

Haplotype diversity of mt<Emphasis Type="Italic">COI</Emphasis> in the fall webworm <Emphasis Type="Italic">Hyphantria cunea</Emphasis> (Lepidoptera: Arctiidae) in introduced regions in China,Iran, Japan,Korea, and its homeland,the United States

Hyphantria cunea (Drury) has colonized many countries outside its native range of North America and has become a model species for studies of the colonization and subsequent adaptation of agricultural pests. Molecular genetic analyses can clarify the origin and subsequent adaptations to non-native habitats. Using the mitochondrial COI gene, we examined the genetic relationships between invasive populations (China, Iran, Japan, and Korea) and native populations (i.e., the United States). The Jilin (China) and Guilan (Iran) populations showed nine previously unknown haplotypes that differed from those found in the south–central United States, suggesting multiple colonization events and different regions of invasion. A dominant mtDNA haplotype in populations in the United States was shared by all of the populations investigated, suggesting that H. cunea with that haplotype have successfully colonized China, Iran, Japan, and Korea.     

Solvent effects on excitation relaxation dynamics of a keto-carotenoid, siphonaxanthin

Solvent effects on relaxation dynamics of a keto-carotenoid, siphonaxanthin, were investigated by means of the femtosecond time-resolved fluorescence spectroscopy. After excitation to the S2 state of siphonaxanthin, the S2-->1(n, pi*) internal conversion occurred with a time constant of 30-35 fs, followed by the 1(n, pi*)-->S1 internal conversion in 180-200 fs. Solvent dependence of the internal conversions was small, however intensities of the S1 fluorescence with its lifetime of longer than 10 ps were enhanced in methanol. These were explained by displacement of the potential surfaces and interaction through the hydrogen-bond between the C=O group of siphonaxanthin and solvents.