Florigen-producing cells express FPF1-LIKE PROTEIN 1 that accelerates flowering and stem growth in long days with sunlight red/far-red ratio in Arabidopsis.

Seasonal changes in spring induce flowering by expressing the florigen, FLOWERING LOCUS T (FT), in Arabidopsis. FT is expressed in unique phloem companion cells with unknown characteristics. The question of which genes are co-expressed with FT and whether they have roles in flowering remains elusive. Through tissue-specific translatome analysis, we discovered that under long-day conditions with the natural sunlight red/far-red ratio, the FT-producing cells express a gene encoding FPF1-LIKE PROTEIN 1 (FLP1). The master FT regulator, CONSTANS (CO), controls FLP1 expression, suggesting FLP1's involvement in the photoperiod pathway. FLP1 promotes early flowering independently of FT, is active in the shoot apical meristem, and induces the expression of SEPALLATA 3 (SEP3), a key E-class homeotic gene. Unlike FT, FLP1 facilitates inflorescence stem elongation. Our cumulative evidence indicates that FLP1 may act as a mobile signal. Thus, FLP1 orchestrates floral initiation together with FT and promotes inflorescence stem elongation during reproductive transitions.

Effects on the growth of carrots (Daucus carota L.), cabbage (Brassica oleracea var. capitata L.) and onion (Allium cepa L.) of restricting the ability of the plants to intercept resources.

The objective of this paper is to assess the size and penetration of edge effects in carrot, cabbage and onion field crops and the extent to which these edge effects are modified by the presence of aerial or soil competition between the crop rows. In all three crops, large weight differences developed between the plants in the edge rows and those in the central rows. There was no indication of plant weight fluctuating between large and small values with each successive row in from the edge, as suggested by others. In carrot and onion, edge effects were greatly reduced by the presence of either white reflective aerial partitions or soil partitions, indicating that these species competed for both light and soil resources in UK field conditions. In cabbage, the mere presence of clear aerial partitions between rows reduced edge effects and there was little effect of soil partitions. This indicates the predominance of shoot over root competition in this species. The differences between species are possibly related to the architectural flexibility of their shoots. These results suggest that, within crops, carrot and onion plants compete for light over a distance of about 20 cm in each direction and for below-ground resources over a distance of about 50 cm in each direction. For cabbage, interactions between plants appeared to be dominated by the requirement for sufficient space to deploy the shoots for efficient light interception.

The parenting experiences of mothers with dissociative disorders.

This article presents a qualitative analysis of the experience of parenting of mothers with dissociative disorders. This analysis was performed to complement the quantitative analysis of problems of mothers with dissociative disorders that Benjamin, Benjamin, and Rind (1996) presented previously. They found that the functioning of these mothers, as well as their subjective experience of mothering, was poorer than that of either clinical or nonclinical control mothers. Our goal was to provide a clearer, richer picture of their problems in parenting. Using the mothers' own words, we describe how the five symptom areas of dissociation (amnesia, depersonalization, derealization, identity confusion, and identity alteration) impeded their parenting efforts. We conclude with a discussion of the necessity of addressing parenting in the treatment of client-mothers with dissociative disorders.

Nucleosomes are not necessary for promoter-proximal pausing in vitro on the Drosophila hsp70 promoter.

RNA polymerase II has been found to pause stably on several metazoan genes in a promoter-proximal region located 20-40 nt downstream from the start site of transcription. Escape of polymerase from this paused state has been proposed to be a rate limiting step in transcription of some genes. A study of the human hsp70 promoter showed that a nucleosome positioned downstream from the transcription start was a key component in establishing a stably paused polymerase in one cell-free system. We tested whether these results could be extended to the Drosophila hsp70 promoter in a Drosophila cell-free system and found that polymerase paused stably on the promoter even when the length of DNA downstream from the transcription start was not sufficient for assembly of a nucleosome. Our results indicate that a downstream nucleosome is not a universal requirement for stably pausing RNA polymerase in the promoter-proximal region.

Dynamic interplay of TFIIA, TBP and TATA DNA.

The TATA binding protein (TBP) binds to the -30 region of eukaryotic and archaea promoters, where it assembles a transcription complex. For those genes transcribed by RNA polymerase II, transcription factor TFIIA binds TBP and positively regulates its activity, including enhancing TBP/ TATA interactions. Since little is known about the dynamic interplay among TFIIA, TBP and DNA, we set out to examine the stability of these interactions. Using the nitrocellulose filter binding assay, the koff of recombinant human TBP from TATA and non-specific DNA was determined to be 5.5(+/-0.1) x 10(-5) s-1 (t1/2 = 210 minutes) and 5.8(+/-0.1) x 10(-4) s-1 (t1/2 = 20 minutes), respectively. TFIIA/TBP complexes, containing either HeLa-derived or recombinant human TFIIA, possessed a nearly tenfold lower koff when bound to TATA. Interactions of TFIIA with DNA upstream of the TATA box did not appear to play a major role in stabilizing TBP/TATA interactions. Instead, the upstream DNA contacts appeared to be important for stabilizing the association of TFIIA with the TBP/TATA complex as measured in electrophoretic mobility shift assays: koff of TFIIA decreased from 1.4(+/-0.1) x 10(-3) s-1 (t1/2 = eight minutes) to 2.4(+/-0.2) x 10(-4) s-1 (t1/2 = 49 minutes) when upstream DNA contacts were allowed. The stability of TFIIA/TBP interactions was measured using a rapid "pull-down" assay, which employed-nickel agarose and polyhistidine-tagged TFIIA. In the absence of DNA, TFIIA dissociated from TBP with a koff = 4.9(+/-0.6) x 10(-3) s-1 (t1/2 = 2.4 minutes), which varied with solution conditions.

Dissociative mothers' subjective experience of parenting.

This study examined to what extent the symptoms of dissociative mothers interfered with their parenting and their subjective experiences of mothering. A group of 54 dissociative inpatient or day-patient mothers, 20 nondissociative inpatient mothers, and 20 hospital staff mothers were screened for Dissociative Disorders using the Structured Clinical Interview for Dissociative Disorders (SCID-D). They were then asked to fill out a self-report questionnaire on various aspects of mothering. This questionnaire, the Subjective Experiences of Parenting Scale (SEPS), examined 14 parenting characteristics: parenting partner support; relative support; abusiveness towards the child; extent to which symptoms interfered with parenting; constructive parenting traits; supportive versus hurtful discipline; extent of showing affection; ability to express affection; attachment behaviors; cognitive distortions; regulation of anger; self versus mother in parenting; subjective experience of mothering; and actions to promote the developmental growth of the child Dissociatives presented significantly more negative parenting behavior and related attributes than staff controls on 13 of the 14 parenting characteristics. Compared to nondissociative patients, the dissociative cohort presented poorer parenting behavior and related attributes on 9 of the 14 characteristics. Overall, the dissociatives experienced more problems with parenting attitudes and behaviors than either comparison group. Dissociative mothers manifested affective, behavioral, and cognitive difficulties in parenting.

A therapy group for mothers with dissociative disorders.

This paper describes the evolution of a therapy group for mothers with dissociative disorders. Although the group is for survivors of childhood trauma, its focus is on the present dilemmas of child rearing rather than on past traumas. It uses mothering as a common bond to improve parenting and interpersonal skills and to propel forward each member's individual therapy. The article summarizes the relevant literature, provides a rationale for such a group, and discusses the issues of cotherapy, combined therapy, group process, transference, countertransference, and thematic material.

Dimerization of the TATA binding protein.

The TATA binding protein (TBP) is a central component of all eukaryotic transcription machineries. The recruitment of TBP to the promoter is slow and possibly rate limiting in transcription complex assembly. In an effort to understand the nature of this potential rate-limiting step, we have investigated the physical state of TBP prior to DNA binding. By chemical cross-linking, gel filtration chromatography, and protein affinity chromatography, we find that the conserved carboxyl-terminal DNA binding domain of human TBP dimerizes when not bound to DNA. The data completely support the proposed dimeric structure of plant TBP, previously determined by x-ray crystallography. TBP dimers are quite stable, having an approximate equilibrium dissociation constant (KD) in the low nanomolar range. The dimerization interface appears to be dominated by hydrophobic forces, as predicted by the crystal structure. TBP dimers do not bind DNA, but they must dissociate into monomers before stably binding to the TATA box. Dissociation of TBP dimers appears to be relatively slow, and as such has the potential to dictate the kinetics of DNA binding.