Revisiting sodium and water reabsorption with functional genomics tools.

PURPOSE OF REVIEW: The kidney plays an essential role in maintaining sodium and water balance, thereby controlling the volume and osmolarity of the extracellular body fluids, the blood volume and the blood pressure. The final adjustment of sodium and water reabsorption in the kidney takes place in cells of the distal part of the nephron in which a set of apical and basolateral transporters participate in vectorial sodium and water transport from the tubular lumen to the interstitium and, finally, to the general circulation. According to a current model, the activity and/or cell-surface expression of these transporters is/are under the control of a gene network composed of the hormonally regulated, as well as constitutively expressed, genes. It is proposed that this gene network may include new candidate genes for salt- and water-losing syndromes and for salt-sensitive hypertension. A new generation of functional genomics techniques have recently been applied to the characterization of this gene network. The purpose of this review is to summarize these studies and to discuss the potential of the different techniques for characterization of the renal transcriptome. RECENT FINDINGS: Recently, DNA microarrays and serial analysis of gene expression have been applied to characterize the kidney transcriptome in different in-vivo and in-vitro models. In these studies, a set of new interesting genes potentially involved in the regulation of sodium and water reabsorption by the kidney have been identified and are currently under detailed investigation. SUMMARY: Characterization of the kidney transcriptome is greatly expanding our knowledge of the gene networks involved in multiple kidney functions, including the maintenance of sodium and water homeostasis.

Leaf-cutting ant attack in initial pine plantations and growth of defoliated plants

The objective of this work was to evaluate the natural attack by Acromyrmex crassispinus in initial Pinus taeda plantations without control measures against ants, as well as the effect of defoliation in seedlings of P. taeda. Evaluations of the attack of leaf-cutting ants on P. taeda plantations were done monthly in the first six months, then 9 and 12 months after planting. The percentages of plants that were naturally attacked by ants were registered. The effect of defoliation was evaluated by artificial defoliation, simulating the natural patterns of attack by A. crassispinus on P. taeda seedlings. The natural attack of A. crassispinus was greater during the first months after planting, being more intense in the first 30 days. Artificial defoliation indicated that there were no significant losses in diameter and height in plants with less than 75% defoliation. However, there were significant losses in diameter and height in plants with 100% defoliation, independently of the cut of the apical meristem, and also plant death. The control of leaf-cutting ants in P. taeda plantings, in which A. crassispinus is the most frequent leaf-cutting ant, should be intense only at the beginning of planting, since the most severe attacks occur during this time.

Structure function relationships of ENaC and its role in sodium handling.

The epithelial sodium channel (ENaC) in the apical membrane of polarized epithelial cells is the rate-limiting step for Na entry into the cell; in series with the basolateral Na pump, it allows the vectorial transepithelial transport of Na ions. ENaC is expressed in different epithelia like the distal nephron or colon, and the airways epithelium. In the lung ENaC controls the composition and the amount of pulmonary fluid, whereas in the distal nephron ENaC under the control of aldosterone and vasopressin, is essential to adapt the amount of Na+ reabsorbed with the daily sodium intake. Activating mutations of ENaC cause severe disturbances of Na+ homeostasis leading to hypertension in human and in mouse models. Functional expression of ENaC in different cell systems allowed the identification of structural domains of the protein that are essential for channel function and/or modulation of channel activity. Site-directed mutations in specific domains of the channel protein lead to channel hyperactivity or channel loss of function. Knowledge about ENaC structure-function relationships opens new opportunities for development of pharmacological tools for controlling ENaC activity, such as channel activators of potential benefit in the treatment of pulmonary edema, or highly potent ENaC blockers with natriuretic effects.

Functional and morphological evidence for a ventricular conduction system in zebrafish and Xenopus hearts.

Zebrafish and Xenopus have become popular model organisms for studying vertebrate development of many organ systems, including the heart. However, it is not clear whether the single ventricular hearts of these species possess any equivalent of the specialized ventricular conduction system found in higher vertebrates. Isolated hearts of adult zebrafish (Danio rerio) and African toads (Xenopus laevis) were stained with voltage-sensitive dye and optically mapped in spontaneous and paced rhythms followed by histological examination focusing on myocardial continuity between the atrium and the ventricle. Spread of the excitation wave through the atria was uniform with average activation times of 20 +/- 2 and 50 +/- 2 ms for zebrafish and Xenopus toads, respectively. After a delay of 47 +/- 8 and 414 +/- 16 ms, the ventricle became activated first in the apical region. Ectopic ventricular activation was propagated significantly more slowly (total ventricular activation times: 24 +/- 3 vs. 14 +/- 2 ms in zebrafish and 74 +/- 14 vs. 35 +/- 9 ms in Xenopus). Although we did not observe any histologically defined tracts of specialized conduction cells within the ventricle, there were trabecular bands with prominent polysialic acid-neural cell adhesion molecule staining forming direct myocardial continuity between the atrioventricular canal and the apex of the ventricle; i.e., the site of the epicardial breakthrough. We thus conclude that these hearts are able to achieve the apex-to-base ventricular activation pattern observed in higher vertebrates in the apparent absence of differentiated conduction fascicles, suggesting that the ventricular trabeculae serve as a functional equivalent of the His-Purkinje system.

Changes of MAP2 phosphorylation during brain development.

The microtubule-associated protein MAP2 is essential for development of early neuronal morphology and maintenance of adult neuronal morphology. Several splice variants exist, MAP2a-d, with a lack of MAP2a in cat brain. MAP2 is widely used as a neuronal marker. In this study we compared five monoclonal antibodies (MAbs) against MAP2. They show differences in the immunocytochemical distribution of MAP2 isoforms during development of the visual cortex and cerebellum of the cat. Local and temporal differences were seen with MAb AP18, an antibody directed against a phosphorylation-dependent epitope near the N-terminal end. In large pyramidal dendrites in visual cortex, the AP18 epitope remained in parts immunoreactive after treatment with alkaline phosphatase. Three MAbs, AP14, MT-01, and MT-02, recognized the central region of the MAP2b molecule, which is not present in MAP2c and 2d, and reacted with phosphorylation-independent epitopes. During the first postnatal week the immunostaining in cerebellum differed between antibodies in that some cellular elements in external and internal granular layers and Purkinje cells were stained to various degrees, whereas at later stages staining patterns were similar. At early stages, antibody MT-02 stained cell bodies and dendrites in cerebral cortex and cerebellum. With progressing maturation, immunoreactivity became restricted to distal parts of apical dendrites of pyramidal cells and was absent from perikarya and finer proximal dendrites in cortex. MT-02 did not stain MAP2 in cerebellum of adult animals. This study demonstrates that the immunocytochemical detection of MAP2 depends on modifications such as phosphorylation and conformational changes of the molecule, and that MAP2 staining patterns differ between MAbs. Phosphorylation and specific conformations in the molecule may be essential for modulating function and molecular stability of MAP2, and monoclonal antibodies against such sites may provide tools for studying the functional role of modifications.

Prevention and management of potential adverse events during transapical aortic valve replacement.

BACKGROUND AND AIM OF THE STUDY: Transapical transcatheter aortic valve replacement (TAVR) is a new minimally invasive technique with a known risk of unexpected intra-procedural complications. Nevertheless, the clinical results are good and the limited amount of procedural adverse events confirms the usefulness of a synergistic surgical/anesthesiological management in case of unexpected emergencies. METHODS: A review was made of the authors' four-year database and other available literature to identify major and minor intra-procedural complications occurring during transapical TAVR procedures. All implants were performed under general anesthesia with a balloon-expandable Edwards Sapien stent-valve, and followed international guidelines on indications and techniques. RESULTS: Procedural success rates ranged between 94% and 100%. Life-threatening apical bleeding occurred very rarely (0-5%), and its incidence decreased after the first series of implants. Stent-valve embolization was also rare, with a global incidence ranging from 0-2%, with evidence of improvement after the learning curve. Rates of valve malpositioning ranged from 0% to < 3%, whereas the risk of coronary obstruction ranged from 0% to 3.5%. Aortic root rupture and dissection were dramatic events reported in 0-2% of transapical cases. Stent-valve malfunction was rarely reported (1-2%), whereas the valve-in-valve bailout procedure for malpositioning, malfunctioning or severe paravalvular leak was reported in about 1.0-3.5% of cases. Sudden hemodynamic management and bailout procedures such as valve-in-valve rescue or cannulation for cardiopulmonary bypass were more effective when planned during the preoperative phase. CONCLUSION: Despite attempts to avoid pitfalls, complications during transapical aortic valve procedures still occur. Preoperative strategic planning, including hemodynamic status management, alternative cannulation sites and bailout procedures, are highly recommended, particularly during the learning curve of this technique.

Multi-scale systems analysis of plant development : beyond cellular signaling and tissue morphodynamics

Les plantes sont essentielles pour les sociétés humaines. Notre alimentation quotidienne, les matériaux de constructions et les sources énergétiques dérivent de la biomasse végétale. En revanche, la compréhension des multiples aspects développementaux des plantes est encore peu exploitée et représente un sujet de recherche majeur pour la science. L'émergence des technologies à haut débit pour le séquençage de génome à grande échelle ou l'imagerie de haute résolution permet à présent de produire des quantités énormes d'information. L'analyse informatique est une façon d'intégrer ces données et de réduire la complexité apparente vers une échelle d'abstraction appropriée, dont la finalité est de fournir des perspectives de recherches ciblées. Ceci représente la raison première de cette thèse. En d'autres termes, nous appliquons des méthodes descriptives et prédictives combinées à des simulations numériques afin d'apporter des solutions originales à des problèmes relatifs à la morphogénèse à l'échelle de la cellule et de l'organe. Nous nous sommes fixés parmi les objectifs principaux de cette thèse d'élucider de quelle manière l'interaction croisée des phytohormones auxine et brassinosteroïdes (BRs) détermine la croissance de la cellule dans la racine du méristème apical d'Arabidopsis thaliana, l'organisme modèle de référence pour les études moléculaires en plantes. Pour reconstruire le réseau de signalement cellulaire, nous avons extrait de la littérature les informations pertinentes concernant les relations entre les protéines impliquées dans la transduction des signaux hormonaux. Le réseau a ensuite été modélisé en utilisant un formalisme logique et qualitatif pour pallier l'absence de données quantitatives. Tout d'abord, Les résultats ont permis de confirmer que l'auxine et les BRs agissent en synergie pour contrôler la croissance de la cellule, puis, d'expliquer des observations phénotypiques paradoxales et au final, de mettre à jour une interaction clef entre deux protéines dans la maintenance du méristème de la racine. Une étude ultérieure chez la plante modèle Brachypodium dystachion (Brachypo- dium) a révélé l'ajustement du réseau d'interaction croisée entre auxine et éthylène par rapport à Arabidopsis. Chez ce dernier, interférer avec la biosynthèse de l'auxine mène à la formation d'une racine courte. Néanmoins, nous avons isolé chez Brachypodium un mutant hypomorphique dans la biosynthèse de l'auxine qui affiche une racine plus longue. Nous avons alors conduit une analyse morphométrique qui a confirmé que des cellules plus anisotropique (plus fines et longues) sont à l'origine de ce phénotype racinaire. Des analyses plus approfondies ont démontré que la différence phénotypique entre Brachypodium et Arabidopsis s'explique par une inversion de la fonction régulatrice dans la relation entre le réseau de signalisation par l'éthylène et la biosynthèse de l'auxine. L'analyse morphométrique utilisée dans l'étude précédente exploite le pipeline de traitement d'image de notre méthode d'histologie quantitative. Pendant la croissance secondaire, la symétrie bilatérale de l'hypocotyle est remplacée par une symétrie radiale et une organisation concentrique des tissus constitutifs. Ces tissus sont initialement composés d'une douzaine de cellules mais peuvent aisément atteindre des dizaines de milliers dans les derniers stades du développement. Cette échelle dépasse largement le seuil d'investigation par les moyens dits 'traditionnels' comme l'imagerie directe de tissus en profondeur. L'étude de ce système pendant cette phase de développement ne peut se faire qu'en réalisant des coupes fines de l'organe, ce qui empêche une compréhension des phénomènes cellulaires dynamiques sous-jacents. Nous y avons remédié en proposant une stratégie originale nommée, histologie quantitative. De fait, nous avons extrait l'information contenue dans des images de très haute résolution de sections transverses d'hypocotyles en utilisant un pipeline d'analyse et de segmentation d'image à grande échelle. Nous l'avons ensuite combiné avec un algorithme de reconnaissance automatique des cellules. Cet outil nous a permis de réaliser une description quantitative de la progression de la croissance secondaire révélant des schémas développementales non-apparents avec une inspection visuelle classique. La formation de pôle de phloèmes en structure répétée et espacée entre eux d'une longueur constante illustre les bénéfices de notre approche. Par ailleurs, l'exploitation approfondie de ces résultats a montré un changement de croissance anisotropique des cellules du cambium et du phloème qui semble en phase avec l'expansion du xylème. Combinant des outils génétiques et de la modélisation biomécanique, nous avons démontré que seule la croissance plus rapide des tissus internes peut produire une réorientation de l'axe de croissance anisotropique des tissus périphériques. Cette prédiction a été confirmée par le calcul du ratio des taux de croissance du xylème et du phloème au cours de développement secondaire ; des ratios élevés sont effectivement observés et concomitant à l'établissement progressif et tangentiel du cambium. Ces résultats suggèrent un mécanisme d'auto-organisation établi par un gradient de division méristématique qui génèrent une distribution de contraintes mécaniques. Ceci réoriente la croissance anisotropique des tissus périphériques pour supporter la croissance secondaire. - Plants are essential for human society, because our daily food, construction materials and sustainable energy are derived from plant biomass. Yet, despite this importance, the multiple developmental aspects of plants are still poorly understood and represent a major challenge for science. With the emergence of high throughput devices for genome sequencing and high-resolution imaging, data has never been so easy to collect, generating huge amounts of information. Computational analysis is one way to integrate those data and to decrease the apparent complexity towards an appropriate scale of abstraction with the aim to eventually provide new answers and direct further research perspectives. This is the motivation behind this thesis work, i.e. the application of descriptive and predictive analytics combined with computational modeling to answer problems that revolve around morphogenesis at the subcellular and organ scale. One of the goals of this thesis is to elucidate how the auxin-brassinosteroid phytohormone interaction determines the cell growth in the root apical meristem of Arabidopsis thaliana (Arabidopsis), the plant model of reference for molecular studies. The pertinent information about signaling protein relationships was obtained through the literature to reconstruct the entire hormonal crosstalk. Due to a lack of quantitative information, we employed a qualitative modeling formalism. This work permitted to confirm the synergistic effect of the hormonal crosstalk on cell elongation, to explain some of our paradoxical mutant phenotypes and to predict a novel interaction between the BREVIS RADIX (BRX) protein and the transcription factor MONOPTEROS (MP),which turned out to be critical for the maintenance of the root meristem. On the same subcellular scale, another study in the monocot model Brachypodium dystachion (Brachypodium) revealed an alternative wiring of auxin-ethylene crosstalk as compared to Arabidopsis. In the latter, increasing interference with auxin biosynthesis results in progressively shorter roots. By contrast, a hypomorphic Brachypodium mutant isolated in this study in an enzyme of the auxin biosynthesis pathway displayed a dramatically longer seminal root. Our morphometric analysis confirmed that more anisotropic cells (thinner and longer) are principally responsible for the mutant root phenotype. Further characterization pointed towards an inverted regulatory logic in the relation between ethylene signaling and auxin biosynthesis in Brachypodium as compared to Arabidopsis, which explains the phenotypic discrepancy. Finally, the morphometric analysis of hypocotyl secondary growth that we applied in this study was performed with the image-processing pipeline of our quantitative histology method. During its secondary growth, the hypocotyl reorganizes its primary bilateral symmetry to a radial symmetry of highly specialized tissues comprising several thousand cells, starting with a few dozens. However, such a scale only permits observations in thin cross-sections, severely hampering a comprehensive analysis of the morphodynamics involved. Our quantitative histology strategy overcomes this limitation. We acquired hypocotyl cross-sections from tiled high-resolution images and extracted their information content using custom high-throughput image processing and segmentation. Coupled with an automated cell type recognition algorithm, it allows precise quantitative characterization of vascular development and reveals developmental patterns that were not evident from visual inspection, for example the steady interspace distance of the phloem poles. Further analyses indicated a change in growth anisotropy of cambial and phloem cells, which appeared in phase with the expansion of xylem. Combining genetic tools and computational modeling, we showed that the reorientation of growth anisotropy axis of peripheral tissue layers only occurs when the growth rate of central tissue is higher than the peripheral one. This was confirmed by the calculation of the ratio of the growth rate xylem to phloem throughout secondary growth. High ratios are indeed observed and concomitant with the homogenization of cambium anisotropy. These results suggest a self-organization mechanism, promoted by a gradient of division in the cambium that generates a pattern of mechanical constraints. This, in turn, reorients the growth anisotropy of peripheral tissues to sustain the secondary growth.

Bud dormancy in apple trees after thermal fluctuations

The objective of this work was to evaluate the effect of heat waves on the evolution of bud dormancy, in apple trees with contrasting chilling requirements. Twigs of 'Castel Gala' and 'Royal Gala' were collected in orchards in Papanduva, state of Santa Catarina, Brazil, and were exposed to constant (3°C) or alternating (3 and 15°C for 12/12 hours) temperature, combined with zero, one or two days a week at 25°C. Two additional treatments were evaluated: constant temperature (3°C), with a heat wave of seven days at 25°C, in the beginning or in the middle of the experimental period. Periodically, part of the twigs was transferred to 25°C for daily budburst evaluation of apical and lateral buds. Endodormancy (dormancy induced by cold) was overcome with less than 330 chilling hours (CH) of constant cold in 'Castel Gala' and less than 618 CH in 'Royal Gala'. A daily 15°C-temperature cycle did not affect the endodormancy process. Heat waves during endodormancy resulted in an increased CH to achieve bud requirements. The negative effect of high temperature depended on the lasting of this condition. Chilling was partly cancelled during dormancy when the heat wave lasted 36 continuous hours or more. Therefore, budburst prediction models need adjustments, mainly for regions with mild and irregular winters, such as those of Southern Brazil.

Relação entre toxicidade de proteínas Vip3Aa e sua capacidade de ligação a receptores intestinais de lepidópteros-praga

Resumo:O objetivo deste trabalho foi avaliar a toxicidade de novas proteínas Vip3Aa e sua capacidade de ligação a vesículas de membrana da microvilosidade apical (VMMA) do intestino de lagartas neonatas de Spodoptera frugiperda, Anticarsia gemmatalise Heliothis virescens. Proteínas expressas pelos genes vip3Aa42 e vip3Aa43 mostraram-se tóxicas a S. frugiperda (CL50 de 78,2 e 113 ng cm-2, respectivamente) e A. gemmatalis(CL50 de 239,2 e 57,5 ng cm-2, respectivamente), e pouco tóxicas a H. virescens (CL50>5.000 ng cm-2). Os ensaios de ligação às VMMA mostraram que as proteínas unem-se de forma efetiva aos receptores nas vesículas das espécies avaliadas, mas essa capacidade de ligação somente é efetiva na ativação da toxicidade para as populações avaliadas de S. frugiperdae A. gemmatalis.

Toxicidade e capacidade de ligação de proteínas Cry1 a receptores intestinais de Helicoverpa armigera (Lepidoptera: Noctuidae)

Resumo: O objetivo deste trabalho foi avaliar a toxicidade e a capacidade de ligação das proteínas Cry1Aa, Cry1Ab, Cry1Ac e Cry1Ca, de Bacillus thuringiensis, a receptores intestinais de Helicoverpa armigera. Realizou-se análise de ligação das proteínas ativadas às vesículas de membrana da microvilosidade apical (VMMA) do intestino médio deH. armigera, além de ensaios de competição heteróloga para avaliar sua capacidade de ligação. Cry1Ac destacou-se como a proteína mais tóxica, seguida por Cry1Ab e Cry1Aa. A proteína Cry1Ca não foi tóxica às lagartas e, portanto, não foi possível determinar os seus parâmetros de toxicidade CL50 e CL90. As proteínas Cry1Aa, Cry1Ab e Cry1Ac são capazes de se ligar a um mesmo receptor nas membranas intestinais, o que aumenta o risco do desenvolvimento de resistência cruzada. Portanto, a utilização conjunta dessas proteínas deve ser evitada.

Diabetes mellitus, periapical inflammation and endodontic treatment outcome

The possible connection between chronic oral inflammatory processes, such as apical periodontitis and periodontal disease (PD), and systemic health is one of the most interesting aspects faced by the medical and dental scientific community. Chronic apical periodontitis shares important characteristics with PD: 1) both are chronic infections of the oral cavity, 2) the Gram-negative anaerobic microbiota found in both diseases is comparable, and 3) in both infectious processes increased local levels of inflammatory mediators may have an impact on systemic levels. One of the systemic disorders linked to PD is diabetes mellitus (DM); is therefore plausible to assume that chronic apical periodontitis and endodontic treatment are also associated with DM. The status of knowledge regarding the relationship between DM and endodontics is reviewed. Upon review, we conclude that there are data in the literature that associate DM with a higher prevalence of periapical lesions, greater size of the osteolityc lesions, greater likelihood of asymptomatic infections and worse prognosis for root filled teeth. The results of some studies suggest that periapical disease may contribute to diabetic metabolic dyscontrol

APLICAÇÃO DA METODOLOGIA DE MODELOS MISTOS (REML/BLUP) NA ESTIMAÇÃO DE COMPONENTES DE VARIÂNCIA E PREDIÇÃO DE VALORES GENÉTICOS EM PUPUNHEIRA (Bactris gasipaes)

No Brasil, a pupunheira é uma planta muito útil na alimentação, seja como fonte de frutos ou de palmito. O interesse pela pupunheira, além de ser uma cultura perene, são: crescimento a pleno sol, precocidade, rusticidade, perfilhamento, palatabilidade e não-escurecimento do palmito após o corte. Estimativas de parâmetros genéticos em pupunheira são escassas e se constituem em ferramenta de suma importância para orientar os programas de melhoramento. O objetivo deste trabalho foi estudar a variabilidade genética e estimar o valor genético individual como critério de seleção, usando o procedimento BLUP/REML (Melhor predição linear não viciada/máxima verossimilhança restrita). Adotaram-se duas estratégias de seleção para o caráter produção de palmito: simulando programa de melhoramento a curto prazo (CP- seleção das 9 famílias com 31 indivíduos de maior valor genético) e a longo prazo (LP- seleção das 15 famílias com 53 indivíduos). As progênies foram avaliadas em experimento delineado em blocos ao acaso com três repetições, parcelas lineares de cinco plantas, espaçadas de 2,0 m x 1,0 m e bordadura composta por uma fileira em torno do experimento no Campo Experimental do Matapí, Município de Porto Grande, Estado do Amapá. A avaliação foi realizada aos 26 meses pós- plantio (2ª avaliação), coletando-se dados de altura da planta (AP), diâmetro da planta à altura do colo (DPC), tamanho do palmito (TP), diâmetro do palmito (DP), peso do resíduo apical (PRA), basal (PRB) e do palmito líquido (PP) (tipo exportação). Os dados de AP, DPC, TP e DP corresponderam às médias das touceiras que apresentavam mais de uma haste. Já para os caracteres PRA, PRB e PP corresponderam à soma das hastes na touceira. De maneira geral, a população estudada apresenta baixa variabilidade genética. As herdabilidades no sentido restrito em nível de indivíduos foram: AP (18,44%), DPC (3,16%), TP (42,47%), DP (10,54%), PP (5,70%), PRB (6,15%). Os ganhos genéticos preditos em relação à média da população para PP foram de 7,18% na situação de LP e 8,40% para CP, com tamanho efetivo de 30,38 e 19,00, respectivamente.

ENRAIZAMENTO DE MINIESTACAS DE AMEIXEIRA

Com este trabalho, objetivou-se maximizar o rendimento do número de estacas enraizadas por ramo. Foram utilizados ramos do ano de duas cultivares de ameixeira (Reubennel e Pluma 7) eliminando-se a porção apical de cada ramo, com diâmetro inferior a 2 mm. As miniestacas foram obtidas fazendo-se um corte em bisel distante no mínimo 0,5 cm acima da gema e outro junto à gema subseqüente. Em seguida, foram mergulhadas em uma solução de ácido indolbutírico (AIB) 2000 mg.L¹, por cinco segundos, e utilizou-se, como testemunha, uma solução composta de água destilada misturada ao mesmo volume de álcool utilizado para diluir o AIB. As miniestacas foram colocadas para enraizar em bandejas de isopor contendo, como substrato, uma mistura de cinza de casca de arroz e vermiculita (2:1 v/v), obedecendo-se à seqüência em que foram retiradas dos ramos. Parte das estacas permaneceram em substrato coberto com plástico transparente com espessura de 20 micra e parte em substrato descoberto. O delineamento experimental foi completamente casualizado, em esquema fatorial 2x2x2 (cultivares, soluções, plástico), com quatro repetições, utilizando-se de 15 miniestacas por parcela. Após 39 dias, foram avaliados o enraizamento (%), o comprimento e o número de raízes. A cultivar Pluma 7 apresenta maior potencial de enraizamento e maior sensibilidade ao AIB. Estacas de gema única possuem capacidade de formar raízes. Toda a extensão do ramo, de cultivares de ameixeiras que respondam ao ácido indolbutírico, pode ser utilizada como estaca na formação de mudas. O plástico reduz o enraizamento de estacas. O AIB aumenta o enraizamento, o número e o comprimento de raízes dos cultivares estudadas.

MULTIPLICAÇÃO E ACLIMATIZAÇÃO DA MACIEIRA INFLUENCIADA PELO TIPO DE EXPLANTE E PELO TEMPO DE PERMANÊNCIA EM MEIO DE CULTURA DE ENRAIZAMENTO

O objetivo do trabalho foi verificar a influência do uso de segmentos de origem basal ou apical na multiplicação in vitro da macieira e do tempo de permanência das brotações em meio de enraizamento na sobrevivência das plantas na aclimatização. Explantes de macieira dos porta-enxertos 'M.111' e 'Marubakaido' de origem basal e apical, com uma gema axilar, foram inoculados em meio de cultura MS, suplementado com 1,0 mg.L-1 de BAP. Após seis semanas, avaliaram-se o número e tamanho de brotações, bem como a formação de gemas. Em seguida, brotações da cv. Marubakaido foram separadas em explantes de 2 a 2,5 cm de comprimento e inoculadas em meio de enraizamento, constituído por ½ MS suplementado com 0,2 mg.L-1 de AIB, onde permaneceram por: 12; 15; 21 e 30 dias. Ao final de cada tratamento, as plântulas foram transplantadas para casa de vegetação onde, após um mês, avaliaram-se a sobrevivência e o peso da matéria seca das raízes e a parte aérea das plantas. Observou-se a formação de brotações em maior número e tamanho quando se utilizaram explantes basais para a cultivar Marubakaido e maior formação de gemas nos explantes da cultivar M.111. Na aclimatização, as plantas apresentaram taxas de sobrevivência superiores a 90%, independentemente do tempo de permanência em meio de enraizamento. Os maiores períodos de permanência das brotações em meio de enraizamento proporcionaram maior peso de matéria seca das raízes e parte-aérea das plantas em casa de vegetação.

CARACTERÍSTICAS FÍSICAS DE PEDÚNCULOS DE CAJUEIRO PARA COMERCIALIZAÇÃO IN NATURA

Com o objetivo de selecionar pedúnculos de cajueiro-anão precoce (Anacardium occidentale L. var. nanum) para comercialização in natura, foram avaliados 09 clones selecionados a partir de um experimento de competição sob irrigação, no município de Mossoró-RN. O clone CCP 76 foi utilizado como testemunha. Os cajus foram colhidos em agosto de 1997 e avaliados quanto às seguintes características: textura, tamanho (diâmetros apical e basal e comprimento), formato, coloração (carta de cores e pigmentos) e peso (total e pedúnculo). Dentre os materiais avaliados, apenas o CCP 09 apresentou cor inferior à testemunha, sendo que os clones CAP 6 (500), END 157, END 189 e END 329 destacaram-se com coloração mais intensa que a mesma. Além da testemunha, apenas os clones END 157, 183 e 189 apresentaram pedúnculos que podem ser classificados como tipo 4 (de maior valor comercial), enquanto, com relação à forma, apenas os clones CAP 6 (500), END 157 e END 183 apresentaram formato piriforme. O clone END 157 apresentou as melhores características para comercialização in natura, inclusive quando comparado à testemunha. Os clones END 183 e 189 apresentaram resultados semelhantes à testemunha, com exceção da cor para o 183 e do formato para o 189.