Phenotypic and genetic characterization of tomato mutants provides new insights into leaf development and its relationship to agronomic traits.

BACKGROUND: Tomato mutants altered in leaf morphology are usually identified in the greenhouse, which demands considerable time and space and can only be performed in adequate periods. For a faster but equally reliable scrutiny method we addressed the screening in vitro of 971 T-DNA lines. Leaf development was evaluated in vitro in seedlings and shoot-derived axenic plants. New mutants were characterized in the greenhouse to establish the relationship between in vitro and in vivo leaf morphology, and to shed light on possible links between leaf development and agronomic traits, a promising field in which much remains to be discovered. RESULTS: Following the screening in vitro of tomato T-DNA lines, putative mutants altered in leaf morphology were evaluated in the greenhouse. The comparison of results in both conditions indicated a general phenotypic correspondence, showing that in vitro culture is a reliable system for finding mutants altered in leaf development. Apart from providing homogeneous conditions, the main advantage of screening in vitro lies in the enormous time and space saving. Studies on the association between phenotype and nptII gene expression showed co-segregation in two lines (P > 99%). The use of an enhancer trap also allowed identifying gain-of-function mutants through reporter expression analysis. These studies suggested that genes altered in three other mutants were T-DNA tagged. New mutants putatively altered in brassinosteroid synthesis or perception, mutations determining multiple pleiotropic effects, lines affected in organ curvature, and the first tomato mutant with helical growth were discovered. Results also revealed new possible links between leaf development and agronomic traits, such as axillary branching, flower abscission, fruit development and fruit cracking. Furthermore, we found that the gene tagged in mutant 2635-MM encodes a Sterol 3-beta-glucosyltransferase. Expression analysis suggested that abnormal leaf development might be due to the lack-off-function of this gene. CONCLUSION: In vitro culture is a quick, efficient and reliable tool for identifying tomato mutants altered in leaf morphology. The characterization of new mutants in vivo revealed new links between leaf development and some agronomic traits. Moreover, the possible implication of a gene encoding a Sterol 3-beta-glucosyltransferase in tomato leaf development is reported.

Approaching the genetic dissection of indirect adventitious organogenesis process in tomato explants.

The screening of 862 T-DNA lines was carried out to approach the genetic dissection of indirect adventitious organogenesis in tomato. Several mutants defective in different phases of adventitious organogenesis, namely callus growth (tdc-1), bud differentiation (tdb-1, -2, -3) and shoot-bud development (tds-1) were identified and characterized. The alteration of the TDC-1 gene blocked callus proliferation depending on the composition of growth regulators in the culture medium. Calli from tds-1 explants differentiated buds but did not develop normal shoots. Histological analysis showed that their abnormal development is due to failure in the organization of normal adventitious shoot meristems. Interestingly, tdc-1 and tds-1 mutant plants were indistinguishable from WT ones, indicating that the respective altered genes play specific roles in cell proliferation from explant cut zones (TDC-1 gene) or in the organization of adventitious shoot meristems (TDS-1 gene). Unlike the previous, plants of the three mutants defective in the differentiation of adventitious shoot-buds (tdb-1, -2, -3) showed multiple changes in vegetative and reproductive traits. Cosegregation analyses revealed the existence of an association between the phenotype of the tdb-3 mutant and a T-DNA insert, which led to the discovery that the SlMAPKKK17 gene is involved in the shoot-bud differentiation process.

Exploratory, anxiety and spatial memory impairments are dissociated in mice lacking the LPA1 receptor.

Lysophosphatidic acid (LPA) is a new, intercellular signalling molecule in the brain that has an important role in adult hippocampal plasticity. Mice lacking the LPA(1) receptor exhibit motor, emotional and cognitive alterations. However, the potential relationship among these concomitant impairments was unclear. Wild-type and maLPA(1)-null mice were tested on the hole-board for habituation and spatial learning. MaLPA(1)-null mice exhibited reduced exploration in a novel context and a defective intersession habituation that also revealed increased anxiety-like behaviour throughout the hole-board testing. In regard to spatial memory, maLPA(1) nulls failed to reach the controls' performance at the end of the reference memory task. Moreover, their defective working memory on the first training day suggested a delayed acquisition of the task's working memory rule, which is also a long term memory component. The temporal interval between trials and the task's difficulty may explain some of the deficits found in these mice. Principal components analysis revealed that alterations found in each behavioural dimension were independent. Therefore, exploratory and emotional impairments did not account for the cognitive deficits that may be attributed to maLPA(1) nulls' hippocampal malfunction.

Temporary inactivation of the supramammillary area impairs spatial working memory and spatial reference memory retrieval.

The aim of our study was to examine the supramammillary (SuM) area involvement in spatial memory. Sprague-Dawley rats with chronically implanted cannula in the supramammillary area were trained in two spatial memory tasks with different memory demands: reference and working memory. In the spatial reference memory task, the rats received microinjections in the SuM area of tetrodotoxin (TTX) (0.5 ng diluted in 0.5 microL of saline) or saline (0.5 microL). The microinjections were administered 30 min before the spatial training (day 4) (to assess the effect on acquisition) and on the following two days (days 5 and 6) the training was conducted without microinjections (to study the effect on consolidation). On the last training day (day 7), in order to assess the retrieval of spatial information, the rats received the microinjections 30 min before the spatial training. The spatial working memory used was a delayed-matching-to-position (DMTP) task. Spatial training was performed for seven days. During the first three days of the spatial training, the rats achieved a good spatial knowledge and learnt the working memory rule necessary to solve the spatial task. On days 4 and 6, the rats received microinjections to study involvement of the SuM area in working memory. The results showed that temporary inactivation of SuM area impairs both the rat's ability to solve a spatial working memory task with DMTP demands and the recovery of spatial information in a spatial reference memory task. We suggest that SuM area is involved in the rearrangement of spatial information during spatial working memory tasks with DMTP memory demands.

Conocimiento sobre VIH-sida en población general de la Ciudad Autónoma de Buenos Aires y su vinculación con variables sociodemográficas / Knowledge about HIV-AIDS in the general population of the Autonomous City of Buenos Aires and its relationship with sociodemographic variables

Resumen La estigmatización ha signado la convivencia con el VIH. Esto repercute negativamente en la salud de las personas positivas e impacta en la población general puesto que, a través del miedo, se puede desalentar el testeo regular y la detección temprana de la infección. Uno de los principales componentes que sostienen la estigmatización es el bajo conocimiento sobre el VIH-sida. El objetivo del presente estudio es indagar el nivel de conocimiento sobre VIH-sida en población de jóvenes y adultos de la Ciudad Autónoma de Buenos Aires y su relación con variables sociodemográficas. Se encuestó a 201 participantes de entre 18 y 60 años inclusive en un diseño muestral por cuotas, preservando la representatividad de la muestra en relación al sexo, edad, nivel de instrucción y nivel socioeconómico. Se advierte en los participantes un escaso nivel de conocimiento sobre la diferencia entre VIH y sida, la PrEP, la PEP y la intransmisibilidad del virus por vía sexual en personas con carga viral indetectable. Por el contrario, se observó mayor conocimiento sobre las vías de transmisión del virus. El género y la edad no se asociaron a diferentes niveles de conocimiento, mientras que los participantes con religión evangélica, un menor nivel de instrucción formal, o un menor nivel socioeconómico mostraron porcentajes inferiores de conocimiento en distintas variables relevadas. Estos resultados enfatizan la necesidad de ejecutar las prerrogativas de la Ley de Educación Sexual Integral en lo concerniente al acceso a información actualizada sobre sexualidad y prevención de infecciones de transmisión sexual.

Abstract Stigmatization has marked the HIV pandemic, and has impacted negatively on the health of people living with HIV and overall population since fear may discourage regular testing and early detection. One of the main components that sustain stigmatization is the scarce knowledge about HIV-AIDS. The aim of this research is to analyze the level of knowledge about HIV-AIDS among the young and adult population dwelling in the Autonomous City of Buenos Aires, and its correlate with sociodemographic variables. 201 participants aged 18 through 60 years old were surveyed in a quota sampling design. The sample representativeness was preserved in relation to sex, age, education, and socioeconomic level. The results revealed that participants have a scarce knowledge about the difference between HIV and AIDS, PrEP, PEP, and the virus non-transmissibility through sexual intercourse with people with undetectable viral load. On the contrary, it was observed greater knowledge about the transmission routes of the virus. Gender and age were not associated with different levels of knowledge, while participants' religion, formal education level, and socioeconomic level are associated with lower percentages of knowledge in the different variables surveyed. These results emphasize the need to fully implement the prerogatives of the Act N°26.150 Comprehensive Sex Education - Argentina, regarding access to updated information on sexuality and prevention of sexually transmitted infections.

Assessing nociceptive sensitivity in mouse models of inflammatory and neuropathic trigeminal pain.

Chronic orofacial pain encompasses a range of debilitating conditions, however in contrast to other body regions, few animal models are available to investigate mechanisms and treatments in the trigeminal area. Particularly, there is a lack of reliable models and testing methods in mice. We have behaviourally tested C57BL/6 mice subjected to unilateral chronic constriction injury (CCI) of the infraorbital nerve (IoN) or unilateral injections of Complete Freunds Adjuvant (CFA) into the vibrissal pad region with the aid of von Frey filaments and air-puffs and the use of a newly designed restraining device. These models were validated by suppressing the pain responses with appropriate drugs. The IoN-CCI group showed significant hyperalgesia on the ipsilateral side in comparison to baseline values for up to 20 days post-CCI following von Frey and air-puff stimulation. Gabapentin (60mg/kg), but not saline, temporarily reversed the hyperalgesia. Animals that received a CFA injection showed hyperresponsivity to both von Frey and air-puff stimulation for up to 4 days post injection. These effects were transiently reversed with 3mg/kg i.p. morphine but not saline. Our study proposes a new restraining device for mice, and validates a behavioural testing procedure of several facial pain models in mice, allowing for reproducible and robust assessment of the effects of pain-related agents and treatments, or phenotyping of genetically modified animals.