Light and soil humidity influencing oak seedling growth and physiology in mixed hardwood gaps. In "S. Rossore, Migliarino, Massaciuccoli" Natural Park (Pisa, I) six-month-old pedunculate oak seedlings (Quercus robur L.) were transplanted within natural gaps of a mixed oak forest. Micro-environmental variability for radiation and water soil content were measured for 145 seedlings during the year. Irradiation relative to the open field (IR) ranged from 5% to 57%. Seven classes of IR each with 20 seedlings were selected. Leaf mass per area was strongly influenced by IR. In the first 3 years survival was high (95, 76 and 75%, respectively) and seedling reached 14±6 cm, 27±13 cm and 39±19 (sd) cm of height. Even if IR and soil water content (SWC) were negatively associated, indicating a lower SWC at the centre of the gaps, height and its relative growth rate increased with IR (explored range: 8-40%) with a significant interaction with SWC in the 1 st year, indicating the positive effect of soil moisture. In the 3 rd year dimensional traits were higher in L+W+ (high light and humidity) followed by L-W+ (low light and high humidity), L+W-and finally by L-W-. Summer drought typical of the Mediterranean climate was evaluated by chlorophyll fluorescence of PSII on apical leaves of seedlings and mature trees at the beginning (21 June) and in mid-summer (20 July). While in June physiological traits did not differ between low and high IR, in mid-summer (at the peak of water-stress) seedlings of the two highest light classes showed chronic photoinhibition (Fv/Fm<0.75) and an increase in thermal dissipation (D) by constitutive term (D c =1-Fv/Fm) and by regulated mechanisms of dissipation through xanthophyll-cycle term (D x ). Moreover, in July seedling leaf physiology largely differed with IR: leaves acclimated to high IR have higher photosynthetic potentialities, as shown by electron transport rate (ETR) and quantum yield (P) at saturating light maintained by an increase of the fraction of open reaction centres (qP), counterbalancing the efficiency decrease of the single reaction centres (Fv'/Fm') dynamically protected via xanthophyll-cycle (D x ). Tree apical leaf physiology behaved differently from seedling leaves both in June (except Fv/Fm) and in July (except D x ). In June photochemistry was higher in tree apical leaves with higher ETR, P, qP and Fv'/Fm' with a lower fraction of energy dissipated and in particular through lower loss by photoprotection through D x as expected for high light conditions without stress; in July no chronic photoinhibition was observed in tree light leaves, the efficiency of single reaction centres (Fv'/Fm') remained high but a drop in the fraction of open centre (qP) decreased significantly P and thus ETR. Consequently the highest potentialities in photochemistry (P) were observed in large gaps (at 40% IR).Keywords: Forest gaps, Natural regeneration, Light environment, Soil humidity, Fluorescence, Oakwood, Quercus robur Received: Feb 25, 2008; Accepted: Apr 29, 2009 Citation: ...

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Foram realizados três experimentos para se avaliar o desenvolvimento in vitro de blastocistos de Mus domesticus domesticus (CF1xSWISS) cultivados a partir de embriões de 1-célula, após exposição e vitrificação em solução crioprotetora contendo 9,0 M de EG acrescido ou não de 0,3 M de SAC. No experimento 1, após o cultivo de 755 embriões de 1-célula, foram observadas taxas de eclosão de 53,0% para o meio HTF e de 61,7% para o meio KSOM (P>0,05), suplementados com 4 mg/ml de BSA + 20 e 25 mM de HEPES. No experimento 2 testaram-se os possíveis efeitos tóxicos ds soluções crioprotetoras propostas: VS1 = 1,8 M EG em PBS + 6% BSA (60 s) seguido de 9,0 M EG em PBS + 6% BSA (imersão direta) e VS2 = 9,0 M EG + 0,3 M SAC em PBS + 6% BSA (imersão direta) em 152 blastocistos cultivdos a partir de embriões de 1-célula em meio KSOM com 25 mM de HEPES. Não houve diferença significativa (P>0,05) entre os grupos controle (86%), VS1 (82,3%) e VS2 (78,4%). No experimento 3, 140 blastocistos cultivados por 72 h em meio KSOM com 4 mg/ml modificadas (OPSm) nas soluções crioprotetoras acima descritas, alcançando taxas de eclosão de 45,7 e 41,4% para VS1 e VS2 (P>0,05), respectivamente. Portanto, concluiu-se que ambos os meios, HTF e KSOM acrescidos de BSA e HEPES, proporcionaram o completo desenvolvimento embrionário in vitro. Apesar de não ter ocorrido diferença estatística (P>0,05), no meio KSOM observou-se que os embriões tiveram uma curva de crescimento mais homogênea e melhores taxas de eclosão, representando mais uma alternativa para o cultivo de embriões de 1-célula. Igualmente, não houve variação significativa (P>0,05) nas taxas de eclosão para os blastocistos de Mus domesticus domesticus vitrificados nas soluções crioprotetoras contendo 9,0 M de EG com ou sem o acréscimo de 0,3 M de SAC.

0,05) entre épocas do ano quando foi comparado o número médio de estruturas por superovulação (5,4 ± 2,63 e 4,3 ± 4,00), o percentual de embriões viáveis (50,0% e 57,6%) e o percentual de prenhezes obtidas: 44,4% e 35,2%, respectivamente. Concluiu-se, portanto, que as diferentes condições climáticas das épocas do ano não influíram nas transferências de embriões em vacas holandesas superovuladas com PMSG.]]>