Search

Abstract Catingueira (Poincianella pyramidalis Tul. L. P. Queiroz) is an endemic species of the Caatinga, with great economic potential. Research on the development of this species under conditions of water restriction, common in the Northeastern semi-arid region, is still scarce. This study evaluated the effects of water restriction on the morphological and biochemical characteristics of catingueira seedlings subjected to water restriction. The experimental design was a randomized complete block design, with five treatments and four replicates. The treatments consisted of periods of water restriction (0, 6, 12, 18 and 24 days without irrigation). The characters evaluated were shoot height, leaf diameter, number of leaves, leaf area, total dry mass, ratio between shoot height and dry mass, Dickson quality index, chlorophylls a and b content, total soluble sugars and free proline. Periods of water restriction longer than six days caused damage to the seedlings development, with reduced growth and quality.

ABSTRACT Combretum leprosum Mart., commonly known as ‘mofumbo’, is used for medicinal purposes, recovery of degraded areas and apiculture. The objective of this study was to evaluate the effect of water stress on the germination and vigor of C. leprosum seeds as function of different temperatures. To compose the treatments, the substrate used was paper roll moistened with polyethylene glycol solutions (PEG 6000), at the following levels of osmotic potential: 0.0; -0.1; -0.2; -0.2; -0.4; and -0.5 MPa, and placed in chamber at constant temperatures of 25, 30 and 35 and alternating temperature of 20-30 °C, forming a 6 x 4 factorial. The seeds were submitted to the following evaluations: germination percentage, germination speed index, root length, shoot length, root dry matter, shoot dry matter. There was a significant interaction for all variables, with a negative effect as the osmotic potentials decreased. Thus, C. leprosum showed high sensitivity to low osmotic potentials, showing a steeper decrease from the potential of -0.2 MPa for all evaluated temperatures. Initial germination and development of C. leprosum seedlings was negatively affected by low osmotic potentials, with a tolerance limit of -0.4 MPa. Temperatures of 25 and 35 °C accentuate the negative effect of the low osmotic potential of water on the germination and early development of C. leprosum seedlings.

The accelerated aging test consists of evaluating the vigor of the seeds under conditions of high temperature and humidity, with the purpose of identifying the physiological quality of lots with similar germination. The objective of this study was to evaluate the efficiency of the accelerated aging test for classifying seed lots of P. moniliformis at different levels of vigor. Initially, the seed lots were assessed by means of seedling emergence, life velocity index, shoot length and root length, total dry mass of seedlings and determination of water content, before and after each period of aging. The experimental design for the whole world was based on a 3 × 4 factorial scheme (three seed lots and four periods of 24, 48, 72 and 96 h duration), with separate evaluations at temperatures of 38 °C and 41 °C. The accelerated aging test conducted at a temperature of 41 °C for 24 h was a more suitable combination for separating batches of P. moniliformis according to different levels of vigour, and made it possible to obtain results similar to the classification of lots in relation to the initial quality.

Moringa (Moringa oleifera Lam.) is an exotic species, from the Indian Northeast, the Moringaceae family and has significant economic importance, with many applications in industry and medi-cine. This species spreads mainly by seed, so obtaining information on the behavior of different temperature and substrate on germination becomes essential since there is no standardized methodology for installation of the germination test. Therefore, this study aimed at evaluating the influence of substrate and temperature on germination and vigor of Moringa oleifera Lam. seeds. The experiment was conducted at the Seed Analysis Laboratory of the Federal Rural University of the Semi-Arid (UFERSA). The statistical design was completely randomized in a 5x2 factorial scheme (temperature x substrate), totaling ten treatments with four replicates of 25 seeds. The substrates were tested roll paper and vermiculite. Then the seeds were incubated at room Bio-chemical Oxygen Demand (B.O.D.) at constant temperatures of 20, 25, 30 and 35 °C and 20-30 °C alternating with a photoperiod of 8 hours. We evaluated the percentage, the average time and the germination speed index and the shoot length and root and total dry weight of seedlings. The roll paper substrate at temperatures of 25 to 30 °C, as well as vermiculite of 30 °C temperature are the most suitable combinations to evaluate germination and vigor of seeds of Moringa oleifera Lam.

The electrical conductivity test is a quick, practical and objective test force; however, its effectiveness varies according to the species, quantity of seed, water volumes, soaking temperature, among other factors. The objective of this study was to evaluate the physiological quality of P.moniliformis seeds lots by means of the electrical conductivity test, testing different methodologies. For this, two lots were tested in three quantities of time (25, 50 and 75 seeds) and nine soaking times (2, 4, 6 , 12, 24 , 36, 48, 60 and 72 hours) in three volumes of water (50, 75 and 100 mL) at 25 °C. To evaluate the initial quality of the lots, germination percentage, germination speed index, average time of germination, length and dry mass of seedlings were determined. The use of the electrical conductivity test of P. moniliformis seeds is recommended using 75 seeds in 75 mL of water for 2 hours at 25 °C or seeds in 50 mL distilled water with 50 seeds per 6 hours at 25 °C.

In this work, we provide evidence for the existence of a nuclear factor involved in the splicing of a specific mitochondrial intron in higher plants. In the Nicotiana sylvestris nuclear NMS1 mutant, defective in both vegetative and reproductive development, the first intron of the nad4 transcript encoding the complex I NAD4 subunit is not removed, whatever the tissue analysed. Transcript patterns of other standard mitochondrial genes are not affected in NMS1. However, numerous polypeptides are missing in two-dimensional in organelle mitochondrial protein synthesis patterns and several nuclear and mitochondrial complex I subunits are present in trace amounts. This indicates that translational or post-translational steps in the synthesis of other mitochondrial proteins are affected. All of these defects co-segregated with the abnormal phenotype in the offspring of a NMS1 x wild-type cross, showing that they are controlled by the same nuclear gene (MS1) or tightly linked loci. Such a complex situation has been described in chloroplasts and mitochondria of fungi, but never in higher plant mitochondria.

We previously reported that the Nicotiana sylvestris CMSII mutant mitochondrial DNA carried a large deletion. Several expressed sequences, most of which are duplicated, and the unique copy of the nad7 gene encoding the NAD7 subunit of the NADH:ubiquinone oxidoreductase complex (complex I) are found in the deletion. Here, we show that the orf87-nad3-nad1/A cotranscription unit transcribed from a unique promoter element in the wild-type, is disrupted in CMSII. Nad3, orf87 and the promoter element are part of the deleted sequence, whilst the nad1/A sequence is present and transcribed from a new promoter brought by the recombination event, as indicated by Northern and primer extension experiments. However, Western analyses of mitochondrial protein fractions and of complex I purified using anti-NAD9 affinity columns, revealed that NAD1 is lacking in CMSII mitochondria. Our results suggest that translation of nad1 transcripts rather than transcription itself could be altered in the mutant. Consequences of lack of this submit belonging the membrane arm of complex I and thought to contain the ubiquinone-binding site, are discussed.

Previous analyses suggested that the Nicotiana sylvestris CMSII mutant carried a large deletion in its mitochondrial genome. Here, we show by cosmid mapping that the deletion is 60 kb in length and contains several mitochondrial genes or ORFs, including the complex I nad7 gene. However, due to the presence of large duplications in the progenitor mitochondrial genome, the only unique gene that appears to be deleted is nad7. RNA gel blot data confirm the absence of nad7 expression, strongly suggesting that the molecular basis for the CMSII abnormal phenotype, poor growth and male sterility, is the altered complex I structure. The CMSII mitochondrial genome appears to consist essentially of one of two subgenomes resulting from recombination between direct short repeats. In the progenitor mitochondrial genome both recombination products are detected by PCR and, reciprocally, the parental fragments are detected at the substoichiometric level in the mutant. The CMSII mtDNA organization has been maintained through six sexual generations.

We previously have shown that Nicotiana sylvestris cytoplasmic male sterile (CMS) mutants I and II present large mtDNA deletions and that the NAD7 subunit of complex I (the main dehydrogenase of the mitochondrial respiratory chain) is absent in CMS I. Here, we show that, despite a large difference in size in the mtDNA deletion, CMS I and II display similar alterations. Both have an impaired development from germination to flowering, with partial male sterility that becomes complete under low light. Besides NAD7, two other complex I subunits are missing (NAD9 and the nucleus-encoded, 38-kDa subunit), identified on two-dimensional patterns of mitochondrial proteins. Mitochondria isolated from CMS leaves showed altered respiration. Although their succinate oxidation through complex II was close to that of the wild type, oxidation of glycine, a priority substrate of plant mitochondria, was significantly reduced. The remaining activity was much less sensitive to rotenone, indicating the breakdown of Complex I activity. Oxidation of exogenous NADH (coupled to proton gradient generation and partly sensitive to rotenone) was strongly increased. These results suggest respiratory compensation mechanisms involving additional NADH dehydrogenases to complex I. Finally, the capacity of the cyanide-resistant alternative oxidase pathway was enhanced in CMS, and higher amounts of enzyme were evidenced by immunodetection.

Unlike other plant species, two copies of nad3 are present in Nicotiana sylvestris mitochondria. Both are localized downstream from an open reading frame (orf87 ), and are associated with either rps12 or the first exon of the nad1 gene. The orf87-nad3-nad1/A cluster is present in normal stoichiometry in Nicotiana tomentosiformis and is sub-stoichiometric in other Solanaceae, revealing recent amplification in the genus Nicotiana. It is suggested from sequence analysis that this cluster originated in an homologous recombination event that involved the nad3-rps12 intergenic region and the upstream region of an ancestral nad1 gene. Transcription patterns and RT-PCR showed that orf87-nad3-rps12 and orf87-nad3-nad1/A clusters are both co-transcription units.

The expression of two mitochondrial gene clusters (orf87-nad3-nad1/A and orf87-nad3-rps12) was studied in Nicotiana sylvestris. 5' and 3' termini of transcripts were mapped by primer extension and nuclease S1 protection. Processing and transcription initiation sites were differentiated by in vitro phosphorylation and capping experiments. A transcription initiation site, present in both gene clusters, was found 213 nucleotides upstream of orf87. This promoter element matches the consensus motif for dicotyledonous mitochondrial promoters and initiates run-off transcription in a pea mitochondrial purified protein fraction. Processing sites were identified 5' of nad3, nad1/A and rps12 respectively. These results suggest that (i) the expression of the two cistrons is only controlled by one duplicated promoter element, and (ii) multiple processing events are required to produce monocistronic nad3, nad1/A and rps12 transcripts.

Use of alcohol and other drugs has been acknowledged as a serious problem among American Indian populations. This study was designed to 1) compare female and male American Indian substance users in residential treatment on psychological (self-esteem, depression, attributional style) and sociocultural (demographics, personal drug use history, family history, acculturation) variables, and 2) examine relationships of the psychological and sociocultural variables with program completion. Results showed that females experienced more family dysfunction (family members misuse of substances, and emotional, physical, and sexual abuse) than males. Both females and males showed positive change on the psychological measures from treatment entry to treatment completion. The factors predicting dropout before program completion were divorce, use of cocaine and depressants, and living in foster care as a child. Implications for prevention, intervention, and training of treatment service providers are discussed.

This study was designed for the purpose of investigating the differences between adolescent substance abstainers, infrequent users, and frequent users on risk factors for substance use related to commitment to education, peer influence, family relationships, and intrapersonal factors. Results from analyses comparing the three groups on the risk factor variables showed that teen substance abstainers and infrequent users are more similar to each other than they are similar to frequent substance users. The study provides support for the contention that preventive efforts may be more successful if targeted at clearly identified groups of problem teen substance users.

How positive and negative life events are perceived by drug abusers in nearly unexplored, yet attribution theory specifies ways in which such perceptions might differentiate drug abusers from nonabusers; it also suggests how attributions might relate to treatment effects and to rehabilitation. This study tested attributions about life events by drug abusers and matched controls as the drug abusers first entered residential treatment, and again later during treatment. Attributions about success and failure in treatment were also assessed. Results showed that attribution processes significantly differentiated drug abusers from controls and that those processes were related to ultimate rehabilitation outcome. Ways in which treatment might be made more effective by focusing on attribution processes are suggested.