Characteristics of Acacia mangium shoot apical meristems in natural and in vitro conditions in relation to heteroblasty

PDF version of the authors can be published in January 2013International audienceMorphological and histocytological characteristics of Acacia mangium shoot apical meristems (SAMs) were assessed in natural and in vitro conditions in relation to heteroblasty. In the natural environment, SAMs with a mature-phyllode morphology were much bigger, contained more cells with larger vacuolated area, or vacuome, and lower nucleoplasmic ratios than those from the juvenile type (Juv). In these latter, nuclei appeared more voluminous, evenly and lightly stained, with clearly distinguishable nucleolei and less abundant chromocenters. In vitro, where reversions from mature to juvenile morphological traits do occur unpredictably, heteroblasty was less obvious in the SAM characteristics examined. In vitro SAMs corresponding to the juvenile and mature types showed similarities with outdoor Juv SAMs, but could be distinguished from these latter by a much larger vacuome that might be induced by the culture conditions. These findings encourage pursuing the investigations at the chromatin and nucleolus level in SAM zones where heteroblasty-related differences have been detected

Specific Nutritional Requirements of Coconut Calli (Cocos nucifera L.) during Somatic Embryogenesis Induction

Summary Coconut calli were cultivated on two somatic embryogenesis induction media (SEIMs), differing in their 2,4-D content. Gain in dry matter weight, composition of soluble sugars within calli, but also pH and contents of glucose and macroelements in media were analysed at O, 15, 28, and 60 days of culture. Relationships between contents of endogenous sugars, on the one hand, and between contents of media macroelements, on the other hand, were analysed. Comparison was made with calli maintained on a control multiplication medium. Traits could be classified into 3 types of response with regard to condition of somatic embryogenesis induction (SEI condition). The first correspond to traits that were modified by the SEI condition and varying over time. Two phases were determined. During the first phase (TO-T15), soluble sugar contents within calli decreased over time. The higher the 2,4-D content in SEIMs, the higher the sugar contents. Consumption of glucose and macroelements in media was negligible. However, strong relationships in the contents of chloride, nitrate, phosphate, and sulfate were modified in the SEI condition. During the second phase (T15-T60, growth became lower in the SEI condition. Requirements for glucose, nitrate and phosphate and acidification .of media were higher. The relationship, determined by changes in nitrate and phosphate (R>0.98), was modified by the SEI conditions, showing a preferential consumption for nitrate in this case. Endogenous sucrose content decreased to become lower in the SEI condition. The higher the 2,4-D content in SEIMs, the higher the requirements for media compounds, the higher the contents of sugars within calli, but the lower the growth. The second type of response corresponded to traits modified by the SEI condition, but constant over time. It concerned relationships between contents of some cations in the media. The third type of response corresponded to traits unchanges by the SEI condition and over time. It concerned the high relationship contents of endogenous glucose and fructose (R = 0.88), and between contents of chloride, ammonium, calcium, magnesium, and potassium. Abbreviations: ANOVA = analysis of variance; ANCOVA = analysis of covariance; BAP = 6-benzylaminopurine; D M W = dry matter weight; FMW = fresh matter weight; % WC = percentage of water content; SEIM = somatic embryogenesis induction medium; TFMW = total fresh matter weight

Guillain-Barre syndrome after lung lobectomy: is there any relationship?

Guillain-Barré syndrome (GBS) is an acute inflammatory polyradiculopathy frequently triggered by infection. It has also been reported in some cases after surgical procedures. We describe the first case of GBS occurring 9 days after lung lobectomy for localized lung cancer and efficiently treated with intravenous immunoglobulins. The exact physiopathology of GBS after surgical procedures is unknown. An immune-mediated process and perioperative infection are the most accepted etiologic hypotheses