The human exosome: an autoantigenic complex of exoribonucleases in myositis and scleroderma

The anti-PM/Scl autoantibodies are known to characterize a subset of autoimmune patients with myositis, scleroderma (Scl), and the PM/Scl overlap syndrome. The major autoantigens that are recognized by anti-PM/Scl autoantibodies are designated PM/Scl-100 and PM/Scl-75. These autoantigens have been reported to associate into a large complex consisting of 11 to 16 proteins and to play a role in ribosome synthesis. Recently, it was discovered that the PM/Scl complex is the human counterpart of the yeast (Saccharomyces cerevisiae) exosome, which is an RNA-processing complex consisting of 11 3' → 5' exoribonucleases. To date, 10 human exosome components have been identified, although only some of these were studied in more detail. In this review, we discuss some recent advances in the characterization of the PM/Scl complex.     

In vitro insect-feeding bioassay to determine the resistance of transgenic rice plants transformed with insect resistance genes against striped stem borer (Chilo suppressalis)

Summary To determine the degree of insect resistance in transgenic plants, different bioassays are used which typically use either whole plant or small pieces of leaves or stems of transgenic plants, following culture under greenhouse conditions. An in vitro insect-feeding bioassay is presented which permits the infestation of transgenic plantlets with newly hatched larvae from the striped stem borer. The bioassay consists of the germination of rice seeds in vitro using Murashige and Skoog medium in test tubes, and then infestation of each 3–4 cm long seedling with one neonate larva obtained from surfacesterilized eggs of Chilo suppressalis. The infested in vitro plantlets are kept in culture rooms at 25°C for several days and then the seedling damage and the growth of the larvae are analyzed. Senia (japonica variety) homozygous transgenic rice plants were used for these experiments. The plants were transformed with either the cry1B or the maize proteinase inhibitor (mpi) genes. Both genes confer resistance to Chilo suppressalis. With non-transformed plants the larvae grew and developed normally, feeding on the small rice plantlets. In contrast, with cry1B plants, the neonate larvae died during the first days of the infestation. These plantlets recovered completely and developed similarly to the non-infested control plants. With transgenic plants transformed with the mpi gene, the neonate larvae did not die but grew more slowly compared with the controls. Thus, this in vitro insect-feeding bioassay is a rapid and easy method to detect the resistance of cry and mpi transgenic plants to stem borers such as Chilo suppressalis.     

Isolation of Bacillus thuringiensis subsp. israelensis from diseased field-collected larvae of the saturniid moth, Hylesia metabus, in French Guiana

Abstract An isolate of Bacillus thuringiensis subsp. israelensis (BTI) was obtained from field-collected larvae of the saturniid moth, Hylesia metabus . This isolate was shown to belong to serotype H 14, and to produce a spherical parasporal body identical to that of the type strain of BTI. With an LC₅₀ of 0.764 μg cm⁻², this isolate was more toxic to H. metabus than the HD-1 strain of B. thuringiensis subsp. kurstaki (HD-1). These results demonstrate that BTI can be active against lepidopterous insects, a wider spectrum of activity than previously realized.     

Total sleep deprivation does not significantly degrade semantic encoding

ABSTRACT

Sleep deprivation impairs performance on cognitive tasks, but it is unclear which cognitive processes it degrades. We administered a semantic matching task with variable stimulus onset asynchrony (SOA) and both speeded and self-paced trial blocks. The task was administered at the baseline and 24 hours later after 30.8 hours of total sleep deprivation (TSD) or matching well-rested control. After sleep deprivation, the 20% slowest response times (RTs) were significantly increased. However, the semantic encoding time component of the RTs remained at baseline level. Thus, the performance impairment induced by sleep deprivation on this task occurred in cognitive processes downstream of semantic encoding.     

Effect of temperature on seed production in the invasive grass Glyceria maxima (Hartm.) Holmb. (Poaceae) in South Africa

Temperature is one of the main factors that determine sexual reproduction in terrestrial and emergent aquatic plant species. The effect of temperature on sexual reproduction and seed production of Glyceria maxima (Hartm.) Holmb. in the southern hemisphere is unknown. Glyceria maxima collections in February 2010 at three isolated infestations in KwaZulu-Natal failed to yield a single seed, only empty panicles. Laboratory experiments showed that vernalisation had no consistent effect on seed production. Field- and laboratory-grown plants produced seeds in the 2010/2011 season, because of having sufficient time at optimum temperatures required for seed production (1 491 and 1 585 hours, respectively), compared to a shorter period (1 352 hours) of suitable temperatures during the 2009/2010 growing season. An inadequate period of optimum temperatures (15–25°C) during seed production resulted in the lack of seeds in the field in the 2009/2010 growing season. This study showed that temperature and duration of exposure thereto during the seed-production period play vital roles in G. maxima sexual reproduction.