RESUMO
The mammalian oocyte is surrounded by a matrix called the zona pellucida (ZP). This envelope participates in processes such as acrosome reaction induction, sperm binding and may be involved in speciation. In cat (Felis catus), this matrix is composed of at least three glycoproteins called ZP2, ZP3, and ZP4. However, recent studies have pointed to the presence of a fourth protein in several mammals (rat, human, hamster or rabbit), meaning that a reevaluation of cat ZP is needed. For this reason, the objective of this research was to analyze the protein composition of cat ZP by means of proteomic analysis. Using ZP from ovaries and oocytes, several peptides corresponding to four proteins were detected, yielding a coverage of 33.17%, 71.50%, 50.23%, and 49.64% for ZP1, ZP2, ZP3, and ZP4, respectively. Moreover, the expression of four genes was confirmed by molecular analysis. Using total RNA isolated from cat ovaries, the complementary deoxyribonucleic acids encoding cat ZP were partially amplified by reverse-transcribed polymerase chain reaction. Furthermore, ZP1 was totally amplified for the first time in this species. As far as we are aware, this is the first study that confirms the presence of four proteins in cat ZP.
Assuntos
Gatos/genética , Proteínas do Ovo/análise , Proteínas do Ovo/genética , Expressão Gênica , Glicoproteínas de Membrana/análise , Glicoproteínas de Membrana/genética , Receptores de Superfície Celular/análise , Receptores de Superfície Celular/genética , Zona Pelúcida/metabolismo , Sequência de Aminoácidos , Animais , Proteínas do Ovo/química , Feminino , Glicoproteínas de Membrana/química , Dados de Sequência Molecular , Fases de Leitura Aberta/genética , Proteômica , RNA Mensageiro/análise , Receptores de Superfície Celular/química , Reação em Cadeia da Polimerase Via Transcriptase Reversa/veterinária , Zona Pelúcida/química , Glicoproteínas da Zona PelúcidaRESUMO
No information exists on the mechanisms developed at the level of leaf water relations by pear-jujube trees (Zizyphus jujuba Mill.) to confront drought. For this reason, the purpose of the present study was to analyse its leaf water relations in order to clarify the resistance mechanisms (avoidance and tolerance) developed in response to a water stress and during recovery. Field-grown 7-year-old pear-jujube trees (cv. Grande de Albatera) were subjected to three irrigation treatments. Control (T0) plants were drip irrigated (112% ETo) in order to guarantee non-limiting soil water conditions, T1 plants (deficit irrigation, 64% ETo) were drip irrigated according to the criteria used by the grower and T2 plants irrigated as T0 but subjected to water withholding for 36 days and a subsequent re-irrigation at the levels used in T0 for 14 days, during the summer of 2011. The results indicated that pear-jujube plants confront water stress by developing stress avoidance and stress tolerance mechanisms. From the beginning of deficit irrigation (T1) and water withholding (T2) to when maximum water stress levels were achieved, leaf turgor was maintained allowing substantial gas exchange levels and, consequently, good leaf productivity. This leaf turgor maintenance was mainly due to two simultaneous and complementary mechanisms. Leaf conductance and the duration of maximum stomatal opening in water stressed plants decreased in order to control water loss via transpiration, contributing to maintain leaf turgor (stress avoidance mechanisms). Also, the gradual recovery of g(l) observed after rewatering the plants can be considered as a mechanism for promoting leaf rehydration. In addition, from the beginning of the stress period, active osmotic adjustment operated, also contributing to the maintenance of leaf turgor (stress tolerance mechanism). The high RWC(a) levels and the possibility of increasing the accumulation of water in the apoplasm in response to water stress, supporting a steeper gradient in water potential between the leaf and the soil, which can be considered another drought tolerance characteristic in pear-jujube.
Assuntos
Folhas de Planta/fisiologia , Água/fisiologia , Ziziphus/fisiologia , Desidratação , Secas , Osmose , Fotossíntese , Folhas de Planta/metabolismo , Caules de Planta/metabolismo , Caules de Planta/fisiologia , Transpiração Vegetal/fisiologia , Fatores de Tempo , Árvores , Ziziphus/metabolismoRESUMO
The water relations of potted tomato plants (Lycopersicon esculentum Mill. cv INCA 9(1)) submitted to two flooding/recovery cycles imposed at the beginning and at the end of photoperiod were studied under controlled conditions. In both experiments, flooding induced stomatal closure due to leaf dehydration linked to a lowered root hydraulic permeability. Thus, during the early hours of flooding there was an effective negative hydraulic message from O(2) deficient roots. However, when the soil was drained stomata did not re-open until some time after leaf water potential and leaf turgor potential returned to normal, supporting the view that chemical messages predominate. Flooding imposed at the end of photoperiod induced a delay in g(l), Psi(l), and Psi(p,) recovery.