Length Of Secondary Branches Research Articles

Morphological effects of estrogen on cholinergic neurons in vitro involves activation of extracellular signal-regulated kinases.

In the present study, we examined the ability of estrogen to enhance cholinergic neurite arborization in vitro and identified the signal transduction cascade associated with this effect. Basal forebrain primordia collected from rat pups on postnatal day 1 were cultured for 2 weeks and then treated with 5 nm 17beta-estradiol for 24 hr. Cholinergic neurons were identified immunocytochemically with an antibody against the vesicular acetylcholine transporter and digitally photographed. Morphological analysis indicated that female cultures respond to estrogen treatment with an increase in total neurite length per neuron (4.5-fold over untreated controls) and in total branch segment number per neuron (2.3-fold over controls). In contrast, there was no change in total neurite length per neuron in male cultures, and we also observed a decrease in total branch segment number per neuron (0.5-fold below controls). Detailed histograms indicated that estrogen increases primary and secondary branch length and number and also increases terminal neuritic branches to the seventh order in female cultures. In a second set of experiments, we investigated the signal transduction cascade involved in this response, and found that an upstream extracellular signal-regulated kinase (ERK) inhibitor blocked the ability of estrogen to enhance outgrowth in female cultures. Our study provides strong evidence in support of the fact that the ERK pathway is required for estrogen-induced structural plasticity in the cholinergic system of female rats. Understanding the intracellular processes that underlie the response of cholinergic neurons to estrogen provides a necessary step in elucidating how cholinergic neurons can be particularly susceptible to degeneration in postmenopausal women.

Seasonal growth of tree lupins (Lupinus arboreus) and the effect of defoliation on leaf production

SummaryThe growth of tree lupins was investigated in two experiments. In the first, two ages of plant, 4‐wk‐old seedlings and 1‐year‐old plants, were transplanted into a ryegrass sward in an upland environment. Growth, in terms of leaf production, branching and stem elongation, was measured over two successive growing seasons. Plant dry matter and nutrient contents were determined at the beginning and end of each growing season. In the first summer, the rate of production of new leaves on the main stem of seedling plants averaged 1.8 leaves per wk and main stem length increased from 5 to 67 cm. On older plants, where floral apices had been initiated on main and primary stems, there was a 3–10 fold increase in secondary branch length. In the second season, there was no effect of plant age on rates of leaf appearance or stem extension; dry matter production was higher than in the first season.In the second experiment, the effect of removal of 0%, 50% or 100% of fully expanded leaves on the subsequent growth of 23‐wk‐old plants was investigated. During the 7‐wk growth period, defoliation promoted the rate of production of mature leaves, and area and dry weight of new laminae were slightly higher in defoliated plants. Defoliation did not affect the concentrations of N, P or K in the new laminae, but P and K concentrations in petioles of defoliated plants were significantly higher than those in intact plants.The results from the experiments are discussed in relation to the potential use of tree lupins as nurse species and biomass crops in hill and upland environments of the UK.

Competition and Growth Form in a Woodland Annual

Distributions of several variables of above-ground growth form, including plant height, vertical distribution of leaf area and vertical distribution of primary and secondary branch length, were compared for crowded (naturally occurring) and uncrowded (naturally occurring and experimentally thinned) populations of Impatiens pallida in south-eastern Pennsylvania. Growth form was examined at the population, individual plant and sub-individual levels. (...)

Genetic analysis for panicle characters in diallel cross of rice

An experiment was carried out to study the genetic components for eight panicle characters in rice using an 8-parent half diallel cross excluding reciprocals during Transplant Aman season, 2003. The parental genotypes used in the study were BRRI dhan29, BR4828-54-4-l-4-9, BRR1 dhan28, 1R8, Amol3, 1R65610-38-2-4-2-6-3, Minikit and ZhongYu7, which were chosen for their diversity in panicle characters. Hayman's analysis of variance (ANOVA) indicated importance of both additive and non-additive genetic components for all the panicle characters except dominance component for filled grains/secondary branches. The ANOVA showed unidirectional dominance for the characters viz, primary branch length, secondary branch length, primary branches/panicle, secondary branches/panicle and filled grains/primary branch, asymmetrical gene distribution for all the panicle traits except filled grains/secondary branch and residual dominance effects for all the panicle characters studied. Two out of eight panicle characters viz., primary branches/panicle and unfilled grains/ secondary branch followed the simple additive-dominance genetic model. The rest of the panicle characters showed nonallelic gene interaction or epistasis. According to Vr-Wr graph, partial dominance was involved in the action of genes governing the inheritance of primary branches/panicle, while complete dominance was involved in the inheritance of unfilled grains/secondary branch. Most of the dominant genes for primary branches/panicle belonged to other hand, 1R8 possessed most of the dominant genes, while 1R65610-38-2-4-2-6-3 possessed most of the recessive genes for unfilled grains/secondary branch. The estimates of components of variance demonstrated involvement of both additive and dominant components in the inheritance of primary branches/panicle and unfilled grains/secondary branch. The distribution of dominant and recessive genes was unequal in the parents for these two characters also. There was drastic influence of environment on these two panicle characters following simple additive-dominance genetic model. Heritability in narrow sense (h2 ns) was very high for primary branches/panicle and unfilled grains/secondary branch. Key Words: Genetic analysis, diallel cross, panicle characters, rice. doi: 10.3329/bjar.v33i4.2307 Bangladesh J. Agril. Res. 33(4) : 631-638, December 2008