Relation entre réaction géotropique et évolution du statenchyme dans la racine d'Asperge

Relationship between the Geotropic Response and the Evolution of the Statenchyma in Roots of Asparagus officinalis. The evolution of the statenchyma in roots of Asparagus of ficinalis seedlings, grown in obscurity, was followed during the first 17 days. After 7 days of etiolation, a decrease of both the average diameter of the amyloplasts and the average number of these organelles was observed in the central root cap cells. If the seedlings were illuminated (with white light) from the 7th day, the average number of statoliths increased rapidly in the statocytes. The volume of these organelles undergoes the same variation in etiolated and in illuminated plants. The initial rate of curvature (V_i) of the roots (stimulated in a horizontal position) and the volume of amyloplasts (V_ac) in their caps were analysed as a function of the time of germination in obscurity (from the 8th to the 17th day). It was found that V_i increased as a linear function of the logarithm of V_ac, which confirms that the weight of the amyloplasts of the statocytes may play a role in the geotropic stimulation of the roots.     

Expression of Three Gastrula Cell Surface Glycoproteins during Embryonic and Larval Development in the Amphibian Pleurodeles waltlii

We have previously reported the identification of cell surface glycoproteins in Pleurodeles waltlii gastrulae. In an attempt to study the expression of three of these cell surface glycoproteins (proteins referred to 1, 11 and 14), we have produced monoclonal and polyclonal antibodies by immunizing mice with the spots of the three selected glycoproteins excised from 2D-gels. Expression of the three glycoproteins was detected on the surfaces of all cells during embryonic development. Before hatching, proteins 1, 11 and 14 become expressed in a limited number of tissues.     

Enzyme histochemistry of the sheep uterus during the oestrous cycle

Enzyme histochemical techniques were applied to frozen sheep uteri from different stages of the oestrous cycle. The localization and activities of succinate, lactate, glucose-6-phosphate, and isocitrate (NADP+) dehydrogenases and acid and alkaline phosphatases were studied in the luminal and glandular epithelia, caruncle and myometrium. Enzyme activity in the sections was scored on a scale of 0--5. In general the enzyme activity in the uterine caruncles and epithelia was higher than in the myometrium. The myometrium did not show any alkaline phosphatase activity and isocitrate dehydrogenase (NADP+) activity was negligible. The low activities of acid phosphatase and lactate dehydrogenase and the moderate levels of glucose-6-phosphate and succinate dehydrogenases in the myometrium were constant. The caruncular tissue showed high levels of phosphatases and glucose-6-phosphate dehydrogenase, moderate levels of lactate and succinate dehydrogenases, and low levels of isocitrate dehydrogenase (NADP+) throughout the oestrous cycle. Much lower phosphatase and isocitrate dehydrogenase (NADP+) levels were found in the epithelium of deep glands compared with superficial glands. The high activity of acid and alkaline phosphatases in the luminal epithelium and the superficial glands was constant from mid-cycle to ovulation, but a significant decrease was observed immediately after ovulation. The level of dehydrogenases in epithelia was generally high and did not change during the oestrous cycle.     

Diversity of metabolic patterns in human brain tumors--I. High energy phosphate compounds and basic composition

Abstract— A total of 25 human brain tumors and 4 specimens of human brain were rapidly frozen at the time of operation and analyzed for ATP, ADP, AMP, UTP, total nucleoside triphosphates, P-creatine, creatine, inorganic P, creatine kinase, lipid and glycogen. Analyses were made on submicrogram samples dissected from frozen dried sections in order to obtain material as free as possible from admixture with brain, necrotic tissue, blood, etc. A method was developed to estimate the original water content of the frozen dried samples. The brain specimens contained five times as much glycogen as small mammal brains, otherwise the values were similar. The tumors were in fair to excellent energy status. Within the areas chosen for assay, most of ATP and total adenylate were substantially higher than in brain in the case of 5 out of 15 gliomas, 3 of 5 meningiomas, and 1 of 4 schwannomas. UTP was almost invariably higher and other nucleotide triphosphates (besides ATP and UTP) lower than in brain. Glycogen was extremely variable, ranging among the gliomas from 0.05% to 6% of dry wt (4 times the level in the human brains). Creatine plus P-creatine, compared to cerebral cortex levels, ranged from 15 to 85% in gliomas, was about 25% in meningiomas and the only medulloblastoma, and varied between 6 and 8% in the schwannomas. P-Creatine varied more or less in keeping with the energy status. Creatine kinase was exceedingly variable. It was almost zero in the schwannomas, the medulloblastomas, 3 of 5 meningiomas, and 2 of 15 gliomas, whereas in some of the gliomas the activity approached that found in brain.     

Intercropping flowering plants in maize systems increases pollinator diversity

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Polymorphism: a weak influence on worker aggregation level in ants

Abstract.  1. Aggregation of individuals, a basic behaviour in social species, plays an essential role in many aspects of animal life (reproduction, defence, and alimentation). Understanding how this phenomenon is modulated is important to comprehend the social organisation of the group.
2. In social insects, aggregation is influenced by environmental (e.g. the light level) and social (e.g. polyethism in monomorphic ants) factors. Ants display a great variation of biological characteristics (e.g. queen number, polymorphism, division of labour, etc.) that are likely to influence the level of inter-attraction and so the aggregation.
3. The present research focused on one biological characteristic: the morphological castes (minors, majors), testing the hypothesis that minors will aggregate more than majors due to their greater need to fight against the loss of heat and to increase their self-protection.
4. Aggregation experiments were conducted on two highly polymorphic species, Atta sexdens rubropilosa and Solenopsis interrupta , using the two extreme morphological castes (majors and minors).
5. All castes exhibited a low level of aggregation: 40–50% of workers assembled for both species, the biggest cluster involving 20% of the total population. The lack of difference between morphological castes in the aggregation shows the weak influence of polymorphism on the interactions between ants.
6. It is concluded that the main factor modulating the aggregation behaviour is polyethism, i.e. the division of labour associated with the presence of an outside-the-nest experience: workers that only take care of the brood, without outside world experience (brood-tenders) assembling more than foraging workers (foragers).     

Asymmetrical costs of sexual conflict in the seaweed fly, Coelopa frigida

Abstract.  1. Sexual conflict can play an important role in the evolution of animal life-history characteristics, including lifespan. Seaweed flies show an increase in mortality rates when exposed to brown algae. The seaweed stimulates females to oviposit and males to mount females. Females typically respond to male mounts by performing a violent rejection response.
2. Here the contribution of sexual conflict to the increase in mortality seen in the presence of seaweed was determined. The survival of single and mixed sex pairs of flies was followed in the presence and absence of seaweed.
3. The two sexes showed differential survival rates, with females living longer in the absence of seaweed. The presence of seaweed reduced survival in both sexes. In the presence of seaweed, female survival was lower when paired with a male. Over 40% of the reduction in survival in females in the presence of seaweed appears to be attributable to sexual conflict.
4. The presence of a female did not significantly affect male survival. Thus the mortality cost of being in the presence of the opposite sex and seaweed appears highly asymmetric.
5. In the presence of seaweed, female survival was lower when females were paired with small males. Small males exhibit higher levels of harassment of females, thus it is argued that pre-copulatory sexual conflict is the probable cause of the increased mortality cost to females of being in the presence of both males and seaweed.