Whole Genome Analysis of Gene Expression Reveals Coordinated Activation of Signaling and Metabolic Pathways during Pollen-Pistil Interactions in Arabidopsis

Plant reproduction depends on the concerted activation of many genes to ensure correct communication between pollen and pistil. Here, we queried the whole transcriptome of Arabidopsis (Arabidopsis thaliana) in order to identify genes with specific reproductive functions. We used the Affymetrix ATH1 whole genome array to profile wild-type unpollinated pistils and unfertilized ovules. By comparing the expression profile of pistils at 0.5, 3.5, and 8.0 h after pollination and applying a number of statistical and bioinformatics criteria, we found 1,373 genes differentially regulated during pollen-pistil interactions. Robust clustering analysis grouped these genes in 16 time-course clusters representing distinct patterns of regulation. Coregulation within each cluster suggests the presence of distinct genetic pathways, which might be under the control of specific transcriptional regulators. A total of 78% of the regulated genes were expressed initially in unpollinated pistil and/or ovules, 15% were initially detected in the pollen data sets as enriched or preferentially expressed, and 7% were induced upon pollination. Among those, we found a particular enrichment for unknown transcripts predicted to encode secreted proteins or representing signaling and cell wall-related proteins, which may function by remodeling the extracellular matrix or as extracellular signaling molecules. A strict regulatory control in various metabolic pathways suggests that fine-tuning of the biochemical and physiological cellular environment is crucial for reproductive success. Our study provides a unique and detailed temporal and spatial gene expression profile of in vivo pollen-pistil interactions, providing a framework to better understand the basis of the molecular mechanisms operating during the reproductive process in higher plants.Fundação para a Ciência e a Tecnologia grants: (FCT–PTDC/QUI/64339/06, SFRH/BD/1128/2000)

Transcriptional profiling of Arabidopsis root hairs and pollen defines an apical cell growth signature

Background: Current views on the control of cell development are anchored on the notion that phenotypes are defined by networks of transcriptional activity. The large amounts of information brought about by transcriptomics should allow the definition of these networks through the analysis of cell-specific transcriptional signatures. Here we test this principle by applying an analogue to comparative anatomy at the cellular level, searching for conserved transcriptional signatures, or conserved small gene-regulatory networks (GRNs) on root hairs (RH) and pollen tubes (PT), two filamentous apical growing cells that are a striking example of conservation of structure and function in plants.Results: We developed a new method for isolation of growing and mature root hair cells, analysed their transcriptome by microarray analysis, and further compared it with pollen and other single cell transcriptomics data. Principal component analysis shows a statistical relation between the datasets of RHs and PTs which is suggestive of a common transcriptional profile pattern for the apical growing cells in a plant, with overlapping profiles and clear similarities at the level of small GTPases, vesicle-mediated transport and various specific metabolic responses. Furthermore, cis-regulatory element analysis of co-regulated genes between RHs and PTs revealed conserved binding sequences that are likely required for the expression of genes comprising the apical signature. This included a significant occurrence of motifs associated to a defined transcriptional response upon anaerobiosis.Conclusions: Our results suggest that maintaining apical growth mechanisms synchronized with energy yielding might require a combinatorial network of transcriptional regulation. We propose that this study should constitute the foundation for further genetic and physiological dissection of the mechanisms underlying apical growth of plant cells

Desempenho produtivo e reprodutivo de ovelhas do grupo "Nativo Pantaneiro" selecionadas como resistentes e susceptíveis a verminose no Mato Grosso do Sul: resultados parciais.

O presente trabalho objetivou avaliar os índices zootécnicos e o parasitismo em ovelhas selecionadas pelo OPG pertencentes ao grupo "nativo pantaneiro". Estão sendo utilizadas 180 ovelhas, oriundas do Pantanal Sul-mato-grossense, estratificadas por peso e pela média de OPG, e classificadas em resistentes (RR), susceptíveis (SS) e intermediárias (RS), submetidas a dois níveis de suplementação proteica: (P) e (P+). A proporção macho/fêmea foi de 1:30, com estação de monta de 30 dias, sincronização do cio e repasse com 14 dias. O anti-helmíntico foi usado, individualmente de acordo com o OPG e o VG. Quanto às médias de natalidade, mortalidade de ovelhas e desmame, o grupo das ovelhas RR apresentou 88%, 6,7% e 78,3%; e das ovelhas SS 85%, 25% e 60%, respectivamente (P<0,05). A taxa de mortalidade de cordeiros até o desmame foi de 11% e 29%, respectivamente para RR e SS (P<0,05). A média de OPG das ovelhas RR (789) foi significativamente menor que do grupo SS (1896) (P<0,05). Em relação ao peso ao nascer e peso aos 30 dias não houve diferenças significativas para o efeito de grupo selecionado, mostrando efeito apenas para OPG (P<0,05). Conforme o resultado parcial dos dados obtidos no primeiro ano de produção observa-se que a seleção dos animais pela contagem de ovos por grama de fezes (OPG) se mostra muito importante nos resultados zootécnicos e econômicos do sistema de produção de ovinos. [Reproductive and productive performance of the "Nativo Pantaneiro" genetic group sheep selected as resistant and susceptible to worms in Mato Grosso do Sul State, Brazil. Partial results]. Abstract: The aim of the present study was to evaluate the performance indexes and parasitism rates by selecting animals for eggs per gram of faeces (EPG) in sheep of the "Nativo Pantaneiro" genetic group. A total of 180 ewe originating from the Pantanal of Mato Grosso do Sul, were stratified by weight and the average of EPG, and classified as resistant (RR), susceptible (SS) and intermediate (RS). These groups were supplemented with two different protein levels: (P) and (P +). The male:female ratio was 1:30, with breeding season, estrus synchronization and return to breeding in 14 days. The anthelmintic was used individually according to the EPG and PVC. Sheep of the group RR had average birth rate, ewe mortality and weaning, respectively as 88%, 6.7% and 78.3%. Sheep from SS group had 85%, 60% and 25%, respectively (P<0 05). The mortality rate of lambs to weaning was 11% in RR group and 29% in SS group (P<0.05). In relation to birth at weight and weight at 30 days there were no significant differences between selected group, showing an effect only for EPG levels (P<0.05). These partial results suggests that animal selection for reproduction by EPG is very important and useful to reach better economic results in ewes production systems

CONSTRUCTAL DESIGN APPLIED TO A FINNED CHANNEL UNDER FORCED CONVECTION FLOWS WITH DIFFERENT IMPOSED PRESSURE DROPS

This paper aims to numerically study the heat transfer in a two dimensional finned channel under laminar, incompressible and forced convective flow with adiabatic walls. The main purpose is to maximize the convection heat transfer by changing the fin’s dimensions by means of Constructal Design. Numerical computations are performed for different Bejan numbers ranging from 0.182 up to 18.2. For all simulations the Prandlt number is kept constant, Pr = 0.71. The fluid motion throughout the channel is caused by imposition of pressure difference between inlet/outlet surfaces. Concerning heat transfer, it is caused by the difference of temperature between the inlet stream of fluid and the heated fins placed at the channel surfaces. The first fin is positioned in the lower surface of the channel while the second one is placed in the upper one. The problem is submitted to three constraints, the channel area (H × L), area of two fins and occupancy areas for the fins. It is considered here that both fins have the same fraction area (ratio between the fins and occupancy areas) f = 0.2. The problem is submitted to three degrees of freedom: H/L (ratio between height and length of channel), H3/L3 and H4/L4 which represent the ratio between the height and length of the first and second fin, respectively. Here, the second fin remains unchanged, being its dimensions H4/L4 = 2.0, whereas the first one is free to modify its dimensions, H3/L3. The channel dimensions are also constant. The solutions are sought using the conservation equations of mass, momentum and energy being these ones discretized through the Finite Volume Method (FVM). Results showed the importance of Constructal Design application for thermal improvement of the problem. Thermal efficiency differences of 5 times where achieved when comparing the best and worst cases. Other important observation is concerned with the effect of ratio H3/L3 over heat transfer ratio (q) which varied significantly from a case where a pressure drop is imposed in the channel to other case where the driven force is caused by imposition of velocity field at the channel inlet

Assessment of greenhouse gases (GHG) emissions from the tallow biodiesel production chain including land use change (LUC).

Economic uncertainties and environmental constraints regarding fossil fuels have encouraged initiatives for renewable energy sources and assessment of their life cycle impacts. Brazil ranks second worldwide in biodiesel production, despite the relatively recent organization of its national chain, marked by the creation of the National Program for Biodiesel Production and Use (PNPB). The Central-West region is responsible for the largest share of biodiesel production (44.4%) and the largest cattle slaughter (37.5%). In this scenario, beef tallow has great potential for expansion of biodiesel production, since it is a byproduct of the chain that, when not properly disposed, presents a considerable environmental burden. This work presents a method for assessing environmental performance that integrates life cycle assessment (LCA) with land use change (LUC) for analysis of the tallow biodiesel production chain. The results are given in terms of increment in annual greenhouse gases (GHG) emissions per hectare related to local tallow biodiesel. The system's boundary covers a representative major cattle farming area in Central-West Brazil. For the LCA segment of the method, five inventory allocations were considered: (i) without allocation, (ii) mass, (iii) market value, (iv) energy and (v) an ?average allocation?, calculated as the mean of mass, market value and energy. The last one is a novel approach proposed in this work, aggregating all the others, which separately result in under or over estimation of impacts. Using the ?average allocation?, the increment in annual GHG emission per hectare from tallow biodiesel production, is 43.2 kg CO2eq ha-1 y-1. This value is 17% less than the emission increment due to soybean biodiesel (50.2 kg CO2eq ha-1 y-1). LUC is responsible for 96% of the emission assessed, which demonstrates the importance of including LUC assessment in life cycle assessment of tallow biodiesel. According to the sensitivity analyses performed, changes from crop to pasture have superior environmental performance among the investigated options. Land use management is essential to preserve the remaining natural areas, making tallow biodiesel more sustainabl