Studies of aberrant phyllotaxy1 Mutants of Maize Indicate Complex Interactions between Auxin and Cytokinin Signaling in the Shoot Apical Meristem

One of the most fascinating aspects of plant morphology is the regular geometric arrangement of leaves and flowers, called phyllotaxy. The shoot apical meristem (SAM) determines these patterns, which vary depending on species and developmental stage. Auxin acts as an instructive signal in leaf initiation, and its transport has been implicated in phyllotaxy regulation in Arabidopsis (Arabidopsis thaliana). Altered phyllotactic patterns are observed in a maize (Zea mays) mutant, aberrant phyllotaxy1 (abph1, also known as abphyl1), and ABPH1 encodes a cytokinin-inducible type A response regulator, suggesting that cytokinin signals are also involved in the mechanism by which phyllotactic patterns are established. Therefore, we investigated the interaction between auxin and cytokinin signaling in phyllotaxy. Treatment of maize shoots with a polar auxin transport inhibitor, 1-naphthylphthalamic acid, strongly reduced ABPH1 expression, suggesting that auxin or its polar transport is required for ABPH1 expression. Immunolocalization of the PINFORMED1 (PIN1) polar auxin transporter revealed that PIN1 expression marks leaf primordia in maize, similarly to Arabidopsis. Interestingly, maize PIN1 expression at the incipient leaf primordium was greatly reduced in abph1 mutants. Consistently, auxin levels were reduced in abph1, and the maize PIN1 homolog was induced not only by auxin but also by cytokinin treatments. Our results indicate distinct roles for ABPH1 as a negative regulator of SAM size and a positive regulator of PIN1 expression. These studies highlight a complex interaction between auxin and cytokinin signaling in the specification of phyllotactic patterns and suggest an alternative model for the generation of altered phyllotactic patterns in abph1 mutants. We propose that reduced auxin levels and PIN1 expression in abph1 mutant SAMs delay leaf initiation, contributing to the enlarged SAM and altered phyllotaxy of these mutants.

Morphological evidences indicate that the interference of cimetidine on the peritubular components is responsible for detachment and apoptosis of Sertoli cells

Cimetidine, referred as antiandrogenic agent, has caused alterations in the seminiferous tubules, including alterations in the peritubular tissue and death of myoid cells by apoptosis. Regarding the structural and functional importance of the peritubular tissue for the maintenance of Sertoli cells (SC), we purpose to investigate the SC-basement membrane interface, focusing the morphological features of SC and their interaction with the basement membrane in the affected tubules by cimetidine. Ten animals were distributed into two groups, control (CG) and cimetidine (CmG) which received saline solution and 50 mg of cimetidine per kg of body weight, respectively, for 52 days. The testes were fixed, dehydrated and embedded for analyses under light and transmission electron microscopy. Paraffin sections were submitted to the TUNEL method; sections of testes embedded in glycol methacrylate were submitted to PAS method and stained by H&E for morphological and quantitative analyses of Sertoli Cells. In the CmG, the SC nuclei were positive to the TUNEL method and showed typical morphological alterations of cell death by apoptosis (from early to advanced stages). A significant reduction in the number of Sertoli Cells was probably due to death of these cells by apoptosis. A close relationship between SC nuclear alterations (including a high frequency of dislocated nuclei from the basal portion) and damage in the peritubular tissue was observed. The ultrastructural analysis showed a parallelism between the gradual advancement of apoptotic process in SC and detachment of the anchoring sites (hemidesmosomes) of SC plasma membrane from the lamina densa. The presence of portions of lamina densa underlying the detached hemidesmosomes indicates a continuous deposition of lamina densa, resulting in the thickening of the basal lamina. The results indicate a possible disarrangement of the SC cytoskeleton, including the focal adhesion structure. These alterations are related to SC apoptosis and probably result from disturbs induced by cimetidine on the peritubular tissue.

Ventilation rates indicate stress-coping styles in Nile tilapia

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Preliminary qualitative analysis on mtDNA in Astyanax fasciatus populations Cuvier, 1819 (Teleostei; Characidae) indicate population distinctiveness

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

DOES SNATCHING FREQUENCY REALLY INDICATE FOOD INGESTION IN THE NILE TILAPIA

The fitness of the snatching frequency as an indicator of food intake in Nile tilapia finger-lings, Oreochromis niloticus (L), was studied. Five groups of four individuals each were used after a two-day starvation period. The hierarchical rank among individuals in the same group was registered. Food in the form of tiny pellets (ranging from 1.30 to 1.95 mm in diameter) was offered, and the individual snatching frequency was observed during a 20-min period. The animals were then sacrificed for evaluation of stomach contents. It was concluded that snatching frequency is not a good parameter to indicate individual food intake in this species when fed as a group with pellets crushed into tiny particles. This raises a problem for investigations that require evaluation of the cumulative effect of competition on food intake, such as growth or conversion efficiency studies. Furthermore, a very low correlation between snatching frequency and food intake was shown in the third hierarchical rank. It is suggested that the linearity assumed in such hierarchies should be reconsidered.

Observations which indicate heterochromatinization of an extra chromosome in the salivary gland cells of Drosophila hybrids

Salivary gland cells of Drosophila mulleri/D. arizonensis aneuploid male hybrids carrying 3 microchromosomes exhibited morphological features which indicate heterochromatinization of one of the small polytene chromosomes. The process apparently changes the chromosome surface producing a coating with a net-like structure and a strong affinity for lacto-acetic orcein. The possibility of a dosage compensatory mechanism operating to counteract the effect of the extra chromosome is discussed on the basis of previous data which indicated that the microchromosomes of these species have ribosomal cistrons and are controlled by regulatory mechanisms especially evident in hybrids. © 1981 Dr W. Junk Publishers.

Sponge spicules indicate Holocene environmental changes on the Nabileque River floodplain, southern Pantanal, Brazil

Sponge spicules are siliceous microfossils that are especially useful for analysis of sandy fluvio-lacustrine sediments. Sponge spicules in a long sediment core (~550 cm below surface), consisting of fine sand, sandy silt, and organic-rich mud, recovered from the floodplain of the Nabileque River, southern Pantanal, Brazil (S20°16′38. 3″/W57°33′00. 0″), form the basis of a novel paleoenvironmental interpretation for this region. Optically stimulated luminescence dates constrain the timing of deposition to the middle-late Holocene and all spicules identified are typical of the Brazilian cerrado biome. The base of the section is dominated by Oncosclera navicella Carter 1881, Metaniaspinata Carter 1881, and Corvospongilla seckti Bonetto and Ezcurra de Drago 1966, which indicate a lotic to semi-lotic environment strongly influenced by an actively meandering river channel at ~6. 7-5. 7 ka BP. The appearance of Heterorotula fistula Volkmer-Ribeiro and Motta 1995, Dosilia pydanieli Volkmer-Ribeiro 1992 and Radiospongilla amazonensis Volkmer-Ribeiro and Maciel 1983 at ~340 cm downcore suggests a reduction in flowing water and a more stable lentic environment, consistent with deposition in an oxbow lake. This oxbow lake environment existed during an interval of regional aridity between ~4. 5 and 3. 9 ka BP. Spicules, as well as phytoliths and diatoms, are highly variable moving up-section, with species from both lotic and lentic ecosystems present. Above ~193 cm, the total abundance of spicules declines, consistent with wetter climate conditions and development of an underfit river similar to the modern floodplain. Results support hypotheses related to migration of the Paraguay River inferred from geomorphological studies and add a key southern-region dataset to the emerging Holocene database of paleoenvironmental records from the Pantanal wetlands. © 2012 Springer Science+Business Media Dordrecht.

Variability in obstacle clearance may (not) indicate cognitive disorders in alzheimer disease

The aim of this study was to investigate obstacle clearance and its variability in individuals with Alzheimer dementia (AD) as well as healthy elderly individuals while they approached and crossed an obstacle in their path. Fifteen people with AD and 15 age-matched/sex-matched healthy individuals (control group) participated in this study. Clinical assessment of both groups was performed by a neuropsychiatrist. Spatial-temporal parameters of 5 trials of unobstructed walking and 5 trials of obstacle crossing during walking (approach and crossing phases) were measured using a 3-dimensional optoelectronic system. The results indicated that individuals with AD showed higher variability in the approach phase for stride length and the horizontal distance from their trailing limb foot to the obstacle. However, their gait variability in the crossing phase was similar to the control group. In addition, the individuals with AD were found to walk slowly and with a short stride length in both conditions. In conclusion, individuals with AD had increased gait variability while approaching an obstacle during walking, indicating a deficit in planning to avoid obstacles that could be related to cognitive disorders. However, gait variability during the crossing phase may not be indicative of cognitive disorders in AD.

The Mycobacterium leprae hsp65 displays proteolytic activity. Mutagenesis studies indicate that the M. leprae hsp65 Proteolytic activity is catalytically related to the HslVU protease?

The present study reports, for the first time, that the recombinant hsp65 from Mycobacterium leprae (chaperonin 2) displays a proteolytic activity toward oligopeptides. The M. leprae hsp65 proteolytic activity revealed a trypsin-like specificity toward quenched fluorescence peptides derived from dynorphins. When other peptide substrates were used (β-endorphin, neurotensin, and angiotensin I), the predominant peptide bond cleavages also involved basic amino acids in P 1, although, to a minor extent, the hydrolysis involving hydrophobic and neutral amino acids (G and F) was also observed. The amino acid sequence alignment of the M. leprae hsp65 with Escherichia coli Hs1VU protease suggested two putative threonine catalytic groups, one in the N-domain (T 136, K 168, and Y 264) and the other in the C-domain (T 375, K 409, and S 502). Mutagenesis studies showed that the replacement of K 409 by A caused a complete loss of the proteolytic activity, whereas the mutation of K 168 to A resulted in a 25% loss. These results strongly suggest that the amino acid residues T 375, K 409, and S 502 at the C-domain form the catalytic group that carries out the main proteolytic activity of the M. leprae hsp65. The possible pathophysiological implications of the proteolytic activity of the M. leprae hsp65 are now under investigation in our laboratory.

Sviluppo di metodologie per la Stima in Tempo Reale delle Grandezze Indicate in Motori a Combustione Interna

Modern Internal Combustion Engines are becoming increasingly complex in terms of their control systems and strategies. The growth of the algorithms’ complexity results in a rise of the number of on-board quantities for control purposes. In order to improve combustion efficiency and, simultaneously, limit the amount of pollutant emissions, the on-board evaluation of two quantities in particular has become essential; namely indicated torque produced by the engine and the angular position where 50% of fuel mass injected over an engine cycle is burned (MFB50). The above mentioned quantities can be evaluated through the measurement of in-cylinder pressure. Nonetheless, at the time being, the installation of in-cylinder pressure sensors on vehicles is extremely uncommon mainly because of measurement reliability and costs. This work illustrates a methodological approach for the estimation of indicated torque and MFB50 that is based on the engine speed fluctuation measurement. This methodology is compatible with the typical on-board application restraints. Moreover, it requires no additional costs since speed can be measured using the system already mounted on the vehicle, which is made of a magnetic pick-up faced to a toothed wheel. The estimation algorithm consists of two main parts: first, the evaluation of indicated torque fluctuation based on speed measurement and secondly, the evaluation of the mean value of the indicated torque (over an engine cycle) and MFB50 by using the relationship with the indicated torque harmonic and other engine quantities. The procedure has been successfully applied to an L4 turbocharged Diesel engine mounted on-board a vehicle.

Forbidden ordinal patterns of periictal intracranial EEG indicate deterministic dynamics in human epileptic seizures

Epileptic seizures typically reveal a high degree of stereotypy, that is, for an individual patient they are characterized by an ordered and predictable sequence of symptoms and signs with typically little variability. Stereotypy implies that ictal neuronal dynamics might have deterministic characteristics, presumably most pronounced in the ictogenic parts of the brain, which may provide diagnostically and therapeutically important information. Therefore the goal of our study was to search for indications of determinism in periictal intracranial electroencephalography (EEG) studies recorded from patients with pharmacoresistent epilepsy.

QUALITY OF LIFE: A POTENTIALLY USEFUL MEASURE TO INDICATE SUBCLINICAL FLARES IN CROHN'S DISEASE

While quality of life (QoL) is a well-recognised outcome measure of Crohn disease (CD) activity, its influence on other outcome measures, including exacerbation of CD is poorly understood. If QoL measures were to be associated with intestinal inflammatory activity, they might be useful for early detection of subclinical flares.

Perfusion-diffusion mismatch in MRI to indicate endovascular treatment of cerebral vasospasm after subarachnoid haemorrhage

Endovascular treatments such as transluminal balloon angioplasty and intra-arterial nimodipine represent rescue therapy for cerebral vasospasm (CVS) after aneurysmal subarachnoid haemorrhage (SAH). Both indication and data regarding its efficacy in the prevention of cerebral infarct are, however, inconsistent. Therefore, an MR based perfusion weighted imaging/diffusion weighted imaging (PWI/DWI) mismatch was used to indicate this treatment and to characterise its effectiveness.

An increase in serum tryptase even below 11.4 ng/mL may indicate a mast cell-mediated hypersensitivity reaction: a prospective study in Hymenoptera venom allergic patients

During a systemic hypersensitivity reaction (SR), an increase in serum tryptase compared to the baseline value is an indicator of mast cell activation, most often due to an IgE-mediated mechanism.