A novel mitotic spindle pole component that originates from the cytoplasm during prophase

Several unique aspects of mitotic spindle formation have been revealed by investigation of an autoantibody present in the serum of a patient with the CREST (calcinosis, Raynaud's phenomenon, esophageal dysmotility, schlerodacytyly, and telangiectasias) syndrome. This antibody was previously shown to label at the spindle poles of metaphase and anaphase cells and to be absent from interphase cells. We show here that the serum stained discrete cytoplasmic foci in early prophase cells and only later localized to the spindle poles. The cytoplasmic distribution of the antigen was also seen in nocodazole-arrested cells and prophase cells in populations treated with taxol. In normal and taxol-treated cells, the microtubules appeared to emanate from the cytoplasmic foci and polar stain, and in cells released from nocodazole block, microtubules regrew from antigen-containing centers. This characteristic distribution suggests that the antigen is part of a microtubule organizing center. Thus, we propose that a prophase originating polar antigen functions in spindle pole organization as a coalescing microtubule organizing center that is present only during mitosis. Characterization of the serum showed reactions with multiple proteins at 115, 110, 50, 36, 30, and 28 kD. However, affinity-eluted antibody from the 115/110-kD bands was shown to specifically label the spindle pole and cytosolic foci in prophase cells.     

Sensitivity to far-red radiation in stomata of Phaseolus vulgaris L.: Rhythmic effects on conductance and photosynthesis

The influence of far-red (FR; 700–800 nm) radiation on steady-state stomatal conductance and net photosynthesis in P. vulgaris has been studied. Whereas FR radiation alone was relatively ineffective, addition of FR to a background of white light (WL; predominantly 400–700 nm) resulted in increased stomatal conductance. Stomata exhibited a marked diurnal sensitivity to FR. The action maximum for enhancing stomatal conductance was near 714 nm. A combination of FR and infra-red (IR; >800 nm) enhanced net photosynthesis when added to a background of WL. When IR alone was added to WL, there was a net decrease in photosynthesis, indicating that it is the FR waveband which is responsible for the observed photosynthetic effects. Naturally occurring levels of FR radiation (235 mol·m^-2·s^-1) in vegetation-canopy shade enhanced net photosynthetic CO₂ gain by 28% when added to a background of 55 mol·m^-2·s^-1 WL.Abbreviations BL blue - FR far-red - IR infra-red - PAR photosynthetically active radiation - R red - WL white light     

Genomic rearrangements in a mouse cell line containing integrated SV40 DNA

In the SV40-transformed mouse embryo fibroblast cell line SVT2/S, genomic rearrangements involving the SV40 DNA and flanking host sequences were identified by Southern blot hybridization using viral DNA as probe. No rearrangements of SV40 DNA integrated into nonpermissive mouse cells have been previously described. The standard arrangement found in the majority of subclones was mapped with 20 restriction enzymes, 10 of which cleave sites within the SV40 DNA. A single copy of a defective integrated viral genome is present, in which the late region is missing from about nucleotide 200 clockwise to about nucleotide 1750. The rest of the viral genome including the origin of replication and T antigen binding region is present and colinear with SV40 DNA, except for an internal repeat of about 1750 bp located between nucleotides 2750 and 4500. Rearrangements were found in 4 out of 20 random subclones of the parental SVT2/S cell line and 3 of the 4 continued to rearrange. The thioguanine-resistant cell line 281-1-4, derived from SVT2/S, remained stable on subculture but a chloramphenicol-resistant mutant, 107-6-4, derived from 281-1-4, was highly unstable. In 107-6-4, unique rearrangements were found in 6 of 31 subclones of a population that had undergone abut 25 doublings from a single-cell isolate. The high rate of rearrangement and the sporadic expression of rearrangement potential are characteristic of the transposable controlling elements discovered by McClintock.     

Trace element concentrations of oligochaetes and relations to sediment characteristics in the reservoir at Altenwörth/Austria

Summary The sediments of the River Danube in the Reservoir at Altenwörth/Lower Austria, are moderately polluted with Zn, Pb, and Cd, whereas concentrations of As, Co, Cr, Cu and Ni are typical of background values. Deposit-feeding oligochaetes living in these sediments were analyzed for their trace element concentrations (As, Cd, Cu, Pb, Zn) to study pathways of recycling of sediment bound amounts to the food web. Compared with background values of benthic deposit feeders from the literature, Cu and As are low, whereas some samples were enhanced in Pb, Cd and Zn. Within the rather narrow concentration ranges, relations of tissue concentrations with chemical and mineralogical compositions of the sediment were hardly found. Increase of clay mineral contents went in parallel with increasing Cd, Zn, and Cu in the tissues, and As in the tissues with total As content. Pb in the tissues was closely related to Pb-concentrations in the pore water. By means of sequential leaching, some further relations between trace element contents in the tissues and solid phases were found. The organic detrital phase positively correlates with As-uptake, whereas hydroxylamine-reducible Mn/Fe-oxyhydroxides influence the Pb-level, and dithionite-reducible Fe/Mn influence the Cu-level. Exchangeable and weak-acid-mobile fractions of the respective metals, however, did not correlate with tissue-levels, nor did the oxalate-extractable Fe-hydroxide coatings, which carry a major part of the heavy metals at fine grain sizes in the Danube sediments investigated. Zn in the tissues was largely independent from all investigated parameters.     

Seasonally modified forms of the revised Janoschek function

Early attempts for modifying growth functions to annual variations dating back up to 2 decades are recalled together with examples for their application showing rather different degrees of approximation. In order to secure independence from special functions, Sager (1982) has proposed a general concept for the modification of growth functions. In this way, examples were treated with the Pütter-Bertalanffy's for crustaceans and clams, with the Gompertz' for the goby, and with the Richards' for the pollack - a near relative of the cod. In continuation of these endevours, the revised Janoschek's is presented in 2 forms, namely one adapted to birth data or in an unbound variant. Special attention is given to the evaluation of the parameters used in nonlinear regressions for both forms. The new equation for bound growth opens a chance for giving real birth values even in seasonally changing growth if one deciding parameter will surmount 1 as has been the case in many applications heretofore. As an example the mussel Mytilus edulis taken from marine "farms" in the Menai-Straits of North Wales is treated with the seasonally modified Janoschek function. Although the special case cannot be realized in this case, the curves for length growth and growth increase are rather instructive compared with the basic behaviour with lacking annual variations. Approximations from 0.5 to 2.7 a show very close agreement with natural values of length as can be verified from numerical and graphical displays.     

Use of a computer to assay motility in bacteria

An assay was developed to study the movement of free-swimming Escherichia coli. Cells were videotaped through a microscope, and the videotape images were then digitized and analyzed with a computer. Angular and linear speeds were measured for wild-type E. coli and for a smooth and a tumbly mutant. The average angular and linear speeds of a population were directly and inversely proportional, respectively, to the time spent tumbling. Changes in angular and linear speeds were followed during the response of wild-type E. coli to attractant or repellent.     

Analysis of 16S-23S rRNA internal transcribed spacer regions in Pasteurellaceae isolated from laboratory rodents

The internal transcribed spacer (ITS) regions of members of Pasteurellaceae isolated from rodents, including the [Pasteurella] pneumotropica biotypes Jawetz and Heyl, [Actinobacillus] muris, "Hemophilus influenzaemurium" and Bisgaard taxon 17 were studied and their feasibility to discriminate these species was analyzed. The reference strains of all species analyzed showed unique species-specific ITS patterns which were further present in 49 clinical isolates of [P.] pneumotropica biotypes Jawetz and Heyl and [A.] muris allowing their identification by comparison to the reference strains pattern. Sequence analysis of the amplified fragments revealed in all species, with exception of "H. influenzaemurium", a larger ITS(ile+ala) which contained the genes for tRNA(Ile(GAU)) and tRNA(Ala(UGC)) and a smaller ITS(glu) with the tRNA(Glu(UUC)) gene. "H. influenzaemurium" revealed two each of the larger and respectively the smaller ITS fragments. Both the length and the sequence of each ITS type were highly conserved within the [P.] pneumotropica biotypes Jawetz and Heyl and [A.] muris strains tested. On the contrary, ITS sequences revealed significant interspecies variations with identity levels ranging from 61.2 to 89.5% for ITS(ile+ala) and 56.5 to 86.8% for ITS(glu). Sequences regions with significant interspecies variation but highly conserved within the species were identified and might be used to design probes for the identification of rodent Pasteurellaceae to the species level.     

Pollination strategies in Cretan Arum lilies

Flowers of the genus Arum are known to attract dung‐breeding flies and beetles through olfactory deceit. In addition to this strategy, the genus has evolved several other pollination mechanisms. The present study aimed to characterize the pollination strategies of the Cretan Arum species by investigating the flowering phenology, thermogeny, inflorescence odours, and the pollinating fauna. The results obtained show that Arum cyrenaicum and Arum concinnatum emit a strong dung smell and exhibit the distinctive features associated with this pollination syndrome. Both species are highly thermogenic, have a similar odour profile and attract small‐bodied Diptera. Although sharing the same habitat, these two plant species are never found growing sympatrically as a result of the early blooming period of A. cyrenaicum. By contrast, Arum creticum and Arum idaeum have evolved a more traditional and mutually beneficial pollination mechanism. The stinking smell has been replaced by a more flower‐like odour that attracts bees (Lasioglossum sp.) and, occasionally, bugs (Dionconotus cruentatus). Although attracting the same pollinator, the main compound present in the odour of A. creticum is different from that of A. idaeum. Principal component analysis (PCA), based on physiologically active components of the flower odours determined by testing on the antenna of the Lasioglossum bee, revealed two different clusters, indicating that pollinators can potentially discriminate between the odours of the two species. A further PCA on the main floral odour volatiles as identified by gas chroatography‐mass spectroscopy from all the Arum species under investigation displayed odour‐based similarities and differences among the species. The PCA‐gas chomotography‐electroantennographic detection active peaks analysis showed that the two species, A. creticum and A. idaeum, form two groups and are clearly separated from A. cyrenaicum and A. concinnatum, which, conversely, cluster together. The evolutionary forces and selective pressures leading to diversification of pollination mechanisms in the Cretan Arum spp. are discussed. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 991–1001.     

High prevalence of autoantibodies to RNA helicase A in Mexican patients with systemic lupus erythematosus

Introduction

Autoantibodies to RNA helicase A (RHA) were reported as a new serological marker of systemic lupus erythematosus (SLE) associated with early stage of the disease. Anti-RHA and other autoantibodies in Mexican SLE patients and their correlation with clinical and immunological features were examined.

Methods

Autoantibodies in sera from 62 Mexican SLE patients were tested by immunoprecipitation of ³⁵S-labeled K562 cell extract and enzyme-linked immunosorbent assay (anti-U1RNP/Sm, ribosomal P, β2GPI, and dsDNA). Anti-RHA was screened based on the immunoprecipitation of the 140-kDa protein, the identity of which was verified by Western blot using rabbit anti-RHA serum. Clinical and immunological characteristics of anti-RHA-positive patients were analyzed.

Results

Anti-RHA was detected in 23% (14/62) of patients, a prevalence higher than that of anti-Sm (13%, 8/62). Prevalence and levels of various autoantibodies were not clearly different between anti-RHA (+) vs. (-) cases, although there was a trend of higher levels of anti-RHA antibodies in patients without anti-U1RNP/Sm (P = 0.07). Both anti-RHA and -Sm were common in cases within one year of diagnosis; however, the prevalence and levels of anti-RHA in patients years after diagnosis did not reduce dramatically, unlike a previous report in American patients. This suggests that the high prevalence of anti-RHA in Mexican patients may be due to relatively stable production of anti-RHA.

Conclusions

Anti-RHA was detected at high prevalence in Mexican SLE patients. Detection of anti-RHA in races in which anti-Sm is not common should be clinically useful. Racial difference in the clinical significance of anti-RHA should be clarified in future studies.