New light on neurocognitive processes linked to autism and attention deficit and hyperactivity disorder in childhood : studies of eye movements in twins

Visual attention and oculomotor response inhibition have been associated with Autism Spectrum Disorder (ASD) and Attention Deficit and Hyperactivity Disorder (ADHD) respectively. The aim of this thesis was to increase our knowledge about these cognitive functions relevant to ASD and ADHD in early infancy and childhood using eye tracking and twin modelling. Study 1 assessed the relative contribution of genetic and environmental influences to attentional networks and visual disengagement (using the gap overlap task) in a sample of twins from the general population, aged 9-14 years. It also assessed whether visual disengagement was associated with autistic traits. Gaze shift latencies across conditions were driven by shared genetic factors. Additionally, there were unique genetic influences to gaze shift latencies in the gap condition. In line with previous work, autistic traits were found to be heritable. There was no association between visual disengagement and autistic traits. Study 2 investigated the relative contribution of genetic and environmental factors to oculomotor response inhibition (using the antisaccade task) and the degree to which oculomotor response inhibition was associated with ADHD traits in the same twin sample. Oculomotor response inhibition in the form of premature anticipatory eye movements was heritable and associated to parent rated inattentive traits. This association was partially due to shared genetic factors. Study 3 investigated how visual disengagement relates to other cognitive developmental processes and behaviors, socioeconomic status and biological sex in early infancy. Gaze shift latencies in the overlap, baseline and gap conditions, of the Gap Overlap task, differed as a function of socioeconomic status and sex. No other associations between visual attention and developmental measures were observed. Thus, in summary, while these findings do not support neither a phenotypic nor a genetic link between visual disengagement and ASD, they support such association between oculomotor response inhibition and inattention (a core component of ADHD). Finally, these findings highlight the influence of sociodemographic factors on individual differences in visual attention in early infancy, thus underscoring the importance of understanding all sources of variation in attentional functions in childhood

Diatomeas epifitas consumidas por adultos de abulón (Haliotis spp.) en Baja California Sur, México

ResumenCon el objetivo de elaborar la lista florística de diatomeas que son consumidas por abulones adultos, se revisaron contenidos intestinales de especímenes silvestres de abulón azul (Haliotis fulgens) y amarillo (H. corrugata), con la hipótesis de que se encontrarían principalmente formas epifitas, sobre todo de Macrocystis pyrifera. Para ello, se hicieron 7 muestreos entre marzo y septiembre de 2012 en La Bocana, BCS, México. En cada muestreo se recolectaron de 4 a 10 especímenes adultos de H. fulgens y H. corrugata. Los organismos se disecaron para extraer sus contenidos intestinales, los cuales se oxidaron con ácido nítrico y alcohol. Las diatomeas montadas con Pleurax se observaron bajo un microscopio con contraste de fases y óptica planapocromática. Así, se elaboró la primera lista florística de diatomeas consumidas por abulones adultos que incluyó 151 taxa (especies y variedades) y 2 nuevos registros para la región: Navicula johanrossi y Navicula cluthensis. Entre los 61 géneros identificados, los mejor representados fueron: Cocconeis (17 especies), Navicula (15), Amphora (15) y Nitzschia (11); la mayoría fueron formas epifitas, aunque no particularmente de M. pyrifera. La alta riqueza de especies observada confirmó que los adultos de Haliotis spp. no son selectivos al consumir diatomeas.AbstractIn order to construct the floristic list of diatoms that are grazed by adult abalone, we examined gut contents of wild specimens of green (Haliotis fulgens) and pink abalone (H. corrugata). The hypothesis that mostly epiphytic forms of diatoms, particularly those from Macrocystis pyrifera would be found in the gut contents was tested. To do that, 7 samplings were carried out between March and September (2012) at La Bocana, BCS, México. Four to ten specimens of H. fulgens and H. corrugata ranging from 96 to 173mm were collected every month approximately. These were dissected and their gut contents extracted, part of which were oxidized in a mixture of commercial alcohol and nitric acid. The cleaned diatoms were mounted on permanent slides using Pleurax mounting media. Diatoms were observed and photographed under a compound microscope with phase contrast and planapochromatic optics. The first floristic list of diatoms that are grazed by adult abalone was thus constructed. This yielded 151 taxa including species and varieties, and 2 new records for the region: Navicula johanrossi and Navicula cluthensis. The best represented among the 61 identified genera were: Cocconeis with 17 especies, Navicula (15), Amphora (15) and Nitzschia (11). These were mostly epiphytic forms, albeit not particularly of M. pyrifera. The high species richness observed confirms that adult Haliotis spp. are not selective when grazing on diatoms

Nuevos registros florísticos de diatomeas bentónicas (Bacillariophyceae) del golfo de California

Background. Most studies on benthic diatoms found in northwestern Mexico have been done along the western coast of the Baja California peninsula. Thus, few studies exist for the Gulf of California. Goals. To gather new records of benthic diatoms found in the Gulf of California. Methods. Diatom samples from sediments and rocks of the coast of Santa Rosalía, Baja California Sur, were observed under a light microscope (LM). Results. Three taxa were recorded and depicted: Caloneis liber var. bicuneata (common), Gyrosigma naja (scarce), and the new combination Entomoneis pulchra var. pulchella (scarce). Conclusions. These three taxa were recorded for the first time in northwestern Mexico.  Antecedentes. Los estudios sobre diatomeas bentónicas para el No­roeste mexicano se han hecho principalmente para la costa occidental de la península de Baja California, pero son pocos para el golfo de Cali­fornia. Objetivos. Presentar nuevos registros de diatomeas bentónicas para el golfo de California. Métodos. Se observaron muestras de diato­meas de sedimentos y rocas de la costa de Santa Rosalía, Baja Califor­nia Sur, México bajo el microscopio de luz. Resultados. Se registraron tres nuevos taxa: Caloneis liber var. bicuneata (común) y Gyrosigma naja (raro), y la nueva combinación Entomoneis pulchra var. pulchella (raro). Conclusiones. Estos tres taxa son registrados por primera vez para la región Noroeste de México

Checklist of the Pteridophytes of Aguascalientes, Mexico

Ferns and fern allies from Agu ascalientes, Mexico were s tudied. Fifty-five localities distributed in all municipios of the state were surveyed. Seventy-seven taxa were found: seventy species of ferns, five species of Selaginell, one species of Equisetum, and one species of Isoëtes. Forty taxa are new records for Aguascalientes. Among the ferns, Cheilanthes and Polypodium are the most diverse and abundant genera, usually occurring in xerophytic associations or dry forests. Selaginella is also common in Aguascalientes, and inhabits rocky cliffs in dry environments. Equisetum and lsoëtes are restricted to marshy places