A complementary role for ELF3 and TFL1 in the regulation of flowering time by ambient temperature

Plants regulate their time to flowering by gathering information from the environment. Photoperiod and temperature are among the most important environmental variables. Sub-optimal, but not near-freezing, temperatures regulate flowering through the thermosensory pathway, which overlaps with the autonomous pathway. Here we show that ambient temperature regulates flowering by two genetically distinguishable pathways, one requiring TFL1 and another requiring ELF3 . The delay in flowering time observed at lower temperatures was partially suppressed in single elf3 and tfl1 mutants, whereas double elf3 tfl1 mutants were insensitive to temperature. tfl1 mutations abolished the temperature response in cryptochrome mutants that are deficient in photoperiod perception, but not in phyB mutants, which have a constitutive photoperiodic response. In contrast to tfl1 , elf3 mutations were able to suppress the temperature response in phyB mutants, but not in cryptochrome mutants. Gene expression profiles revealed that the tfl1 and elf3 effects are due to the activation of different sets of genes, and identified CCA1 and SOC1/AGL20 as being important cross-talk points. Finally, genome-wide gene expression analysis strongly suggests a general and complementary role for ELF3 and TFL1 in temperature signalling.     

Gastric Juice Polymerase Chain Reaction: An Alternative to Histology in the Diagnosis of Helicobacter pylori Infection

Background. Infection from Helicobacter pylori plays a role in several gastroduodenal diseases. The recent availability of molecular techniques, particularly the polymerase chain reaction (PCR), allows us to detect small amounts of this bacterium. The aims of this study were to compare PCR and histological findings and to ascertain the clinical usefulness of H. pylori PCR identification in different biological samples.
Materials and Methods. We studied 94 consecutive patients. Saliva, gastric juice, and four antral and four body biopsies were obtained from each patients. H. pylori was evaluated histologically in two antral and two body biopsies (Giemsa or Warthin-Starry stain). After extraction, DNA was submitted for PCR amplification using the two primers HPU1 and HPU2, which amplified a 411-bp product from the urease gene A.
Results. Forty-nine patients were H. pylori -positive at histological workup. The sensitivity of PCR was 92% for gastric juice, 73% for antral biopsies, 61% for body biopsies, and 13% for saliva. Of the 45 H. pylori -negative patients at histological assessment, 7 (16%) had positive findings on PCR, mainly when gastric juice was examined.
Conclusions. These results indicate that PCR is as sensitive as histological assessment. We suggest that PCR H. pylori detection in gastric juice is a sensitive method for diagnosing this infection.     

The GURKE gene is required for normal organization of the apical region in the Arabidopsis embryo

Dicot plant embryos undergo a transition from radial to bilateral symmetry. In Arabidopsis, this change reflects patterning within the apical region, resulting in the formation of the cotyledon and shoot meristem primordia. Mutations in the GURKE gene give seedlings with highly reduced or no cotyledons. Both strong and weak gurke alleles confer this phenotypic variability although strong alleles often eliminate the entire apex and sometimes also part of the hypocotyl. The root and the root meristem as well as the radial pattern of concentric tissue layers are essentially normal. The mutant seedling phenotype can be traced back to the triangular/early-heart stage of embryogenesis when abnormal cell divisions occur within the apical region such that no or only rudimentary cotyledon primordia are established. The postembryonic development of gurke seedlings was examined in culture. In weak alleles, apical growth gave rise to abnormal leaves and stem-like structures and, eventually, abnormal flowers. In strong alleles, the apical region often failed to grow but occasionally produced fused leaf-like structures with no dorso-ventral polarity and a totally unorganized vascular system while no stems developed. The observations suggest that the GURKE gene is involved primarily in the organization of the apical region in the embryo and may also play a role during postembryonic development.     

Cytosolic and chloroplastic glutamine synthetase of sugarbeet (Beta vulgaris) respond differently to organ ontogeny and nitrogen source

Changes in the activity and subunit composition of cytosolic glutamine synthetase (GS 1; EC 6.3.1.2) and chloroplastic GS (GS 2) were studied in response to an internal (organ ontogeny) and external signal (N source: NO₃⁻ or NH₄⁺). Maximum GS 1 activity of all organs examined was measured in the fibre roots, irrespective of the N source. The response of GS 1 to the N source was, however, organ specific. In the fibre roots, NH₄⁺ nutrition resulted in a 2- to 7-fold (based on protein or freshweight, respectively) increase of GS 1 activity compared to NO₃⁻-grown plants. In contrast to the roots, GS 1 activity in the leaf blades was 2-fold lower with NH₄⁺ nutrition, whereas only minor changes occurred in the petioles. GS 2 activity was highest in the mature and senescing leaf blade; activity was 2-fold higher with NH₄⁺ than with NO₃⁻ nutrition. Not only activity, but also subunit composition of GS 1 changed during organ ontogeny as well as in response to the N source. In contrast to GS 1, only minor changes were evident in GS 2 subunit composition, despite significant changes in GS 2 activity. Up to 5 different GS 1 subunits of ≈41–43 kDa were separated; they were identical in all organs examined. GS 2 was composed of 4 different subunits of ≈48 kDa.     

Resource partitioning of the host fungus Coriolus versicolor by two ciid beetles: the role of odour compounds and host ageing

The ciid beetles Octotemnus glabriculus and Cis boleti exploit different developmental stages of fruit bodies of their preferred host fungus Coriolus versicolor . Larvae of the smaller beetle, O. glabriculus , mainly use young, expanding, fruit bodies; adults of O. glabriculus are predominantly found in young fruit bodies. By contrast, adults and larvae of the larger beetle, C. boleti , are prevalent in fully developed fruit bodies of C. versicolor . Because fruit bodies of most genets emerge during spring and early summer and mature by autumn, O. glabriculus and C. boleti breed in separated seasons. Adults and larvae of O. glabriculus are abundant in spring and early summer. By contrast, the number of adults and larvae of C. boleti increases gradually from late spring to summer and peaks in autumn. We conducted a field experiment that suggests that the phenological dynamics of C. versicolor fruit bodies drive the separation of breeding seasons between O. glabriculus and C. boleti . Additionally, laboratory experiments revealed that O. glabriculus and C. boleti have differential behavioural responses to odour compounds from young and mature fruit bodies of C. versicolor . We conclude that age-related changes in the chemical composition of fruit bodies may allow O. glabriculus and C. boleti to discriminate among C. versicolor , thus providing a mechanism for the partitioning of the resource.     

Effects of fenfluramine and ritanserin on prolactin response to insulin-induced hypoglycemia in obese patients: evidence for failure of the serotoninergic system

In order to study the hypothesized impairment of the serotoninergic system in human obesity, an insulin tolerance test (ITT) was carried out on 12 obese normoprolactinemic women and on 6 normal-weight women before (A) and after (B) the administration of a serotoninergic drug, fenfluramine (60 mg twice a day per os for 7 days). After a washout period, a new ITT (C) followed the administration of fenfluramine at the same dose, associated with a specific S2 blocker receptor agent, ritanserin (30 mg/day for the first 2 days and 20 mg/day for a further 5 days). In obese subjects, the prolactin (PRL) response to ITT A was reduced as compared to the controls: in 6 patients ('nonresponders') the PRL levels did not change, while in the other 6 ('responders') they increased (p less than 0.003) but less than in the controls (p less than 0.02). In normal-weight subjects, the administration of fenfluramine alone or with ritanserin did not modify the PRL response to ITT. In the responders, the serotoninergic drug normalized the PRL response to ITT while significantly improving it in the nonresponders; these effects were not antagonized by ritanserin. In conclusion, our data suggest that the serotoninergic system of obese patients is impaired and that the different secretory pattern observed in the two groups before and after fenfluramine may reflect differing degrees of this impairment.     

A novel δ° arising from a frameshift insertion,detected by direct sequencing of enzymatically amplified DNA

Summary DNA fingerprints were generated from various human somatic tissues and from peripheral blood of 179 children and their 80 parents using (CAC)₅/(GTG)₅ oligonucleotide probes. Whereas somatic stability of the fingerprint patterns was demonstrated, the average rate for germline mutations was estimated to be approximately 0.001 per DNA locus and gamete, with the three different restriction enzymes used. Seven out of eight mutations observed appeared to be of paternal origin.