Recruitment and regulation of phosphatidylinositol phosphate kinase type 1 gamma by the FERM domain of talin

Membrane phosphoinositides control a variety of cellular processes through the recruitment and/or regulation of cytosolic proteins. One mechanism ensuring spatial specificity in phosphoinositide signalling is the targeting of enzymes that mediate their metabolism to specific subcellular sites. Phosphatidylinositol phosphate kinase type 1 gamma (PtdInsPKI gamma) is a phosphatidylinositol-4-phosphate 5-kinase that is expressed at high levels in brain, and is concentrated at synapses. Here we show that the predominant brain splice variant of PtdInsPKI gamma (PtdInsPKI gamma-90) binds, by means of a short carboxy-terminal peptide, to the FERM domain of talin, and is strongly activated by this interaction. Talin, a principal component of focal adhesion plaques, is also present at synapses. PtdInsPKI gamma-90 is expressed in non-neuronal cells, albeit at much lower levels than in neurons, and is concentrated at focal adhesion plaques, where phosphatidylinositol-4,5-bisphosphate has an important regulatory role. Overexpression of PtdInsPKI gamma-90, or expression of its C-terminal domain, disrupts focal adhesion plaques, probably by local disruption of normal phosphoinositide balance. These findings define an interaction that has a regulatory role in cell adhesion and suggest new similarities between molecular interactions underlying synaptic junctions and general mechanisms of cell adhesion.     

Postcranial evidence from early Homo from Dmanisi, Georgia

The Plio-Pleistocene site of Dmanisi, Georgia, has yielded a rich fossil and archaeological record documenting an early presence of the genus Homo outside Africa. Although the craniomandibular morphology of early Homo is well known as a result of finds from Dmanisi and African localities, data about its postcranial morphology are still relatively scarce. Here we describe newly excavated postcranial material from Dmanisi comprising a partial skeleton of an adolescent individual, associated with skull D2700/D2735, and the remains from three adult individuals. This material shows that the postcranial anatomy of the Dmanisi hominins has a surprising mosaic of primitive and derived features. The primitive features include a small body size, a low encephalization quotient and absence of humeral torsion; the derived features include modern-human-like body proportions and lower limb morphology indicative of the capability for long-distance travel. Thus, the earliest known hominins to have lived outside of Africa in the temperate zones of Eurasia did not yet display the full set of derived skeletal features.     

A complete human pelvis from the Middle Pleistocene of Spain.

The Middle Pleistocene site of Sima de los Huesos in Sierra de Atapuerca, Spain, has yielded around 2,500 fossils from at least 33 different hominid individuals. These have been dated at more than 200,000 years ago and have been classified as ancestors of Neanderthals. An almost complete human male pelvis (labelled Pelvis 1) has been found, which we associate with two fragmentary femora. Pelvis 1 is robust and very broad with a very long superior pubic ramus, marked iliac flare, and a long femoral neck. This pattern is probably the primitive condition from which modern humans departed. A modern human newborn would pass through the birth canal of Pelvis 1 and this would be even larger in a female individual. We estimate the body mass of this individual at 95 kg or more. Using the cranial capacities of three specimens from Sima de los Huesos, the encephalization quotients are substantially smaller than in Neanderthals and modern humans.     

Recurrent gross mutations of the PTEN tumor suppressor gene in breast cancers with deficient DSB repair

Basal-like breast cancer (BBC) is a subtype of breast cancer with poor prognosis. Inherited mutations of BRCA1, a cancer susceptibility gene involved in double-strand DNA break (DSB) repair, lead to breast cancers that are nearly always of the BBC subtype; however, the precise molecular lesions and oncogenic consequences of BRCA1 dysfunction are poorly understood. Here we show that heterozygous inactivation of the tumor suppressor gene Pten leads to the formation of basal-like mammary tumors in mice, and that loss of PTEN expression is significantly associated with the BBC subtype in human sporadic and BRCA1-associated hereditary breast cancers. In addition, we identify frequent gross PTEN mutations, involving intragenic chromosome breaks, inversions, deletions and micro copy number aberrations, specifically in BRCA1-deficient tumors. These data provide an example of a specific and recurrent oncogenic consequence of BRCA1-dependent dysfunction in DNA repair and provide insight into the pathogenesis of BBC with therapeutic implications. These findings also argue that obtaining an accurate census of genes mutated in cancer will require a systematic examination for gross gene rearrangements, particularly in tumors with deficient DSB repair.     

Cavity solitons as pixels in semiconductor microcavities

Cavity solitons are localized intensity peaks that can form in a homogeneous background of radiation. They are generated by shining laser pulses into optical cavities that contain a nonlinear medium driven by a coherent field (holding beam). The ability to switch cavity solitons on and off and to control their location and motion by applying laser pulses makes them interesting as potential 'pixels' for reconfigurable arrays or all-optical processing units. Theoretical work on cavity solitons has stimulated a variety of experiments in macroscopic cavities and in systems with optical feedback. But for practical devices, it is desirable to generate cavity solitons in semiconductor structures, which would allow fast response and miniaturization. The existence of cavity solitons in semiconductor microcavities has been predicted theoretically, and precursors of cavity solitons have been observed, but clear experimental realization has been hindered by boundary-dependence of the resulting optical patterns-cavity solitons should be self-confined. Here we demonstrate the generation of cavity solitons in vertical cavity semiconductor microresonators that are electrically pumped above transparency but slightly below lasing threshold. We show that the generated optical spots can be written, erased and manipulated as objects independent of each other and of the boundary. Numerical simulations allow for a clearer interpretation of experimental results.     

Breeding and parental care in the endangered Tehuantepec jackrabbit ( Lepus flavigularis )

We documented date and duration of each breeding phase, breeding rate, nursing behavior, parental care, and leveret survival of the Tehuantepec jackrabbit ( Lepus flavigularis ), a critically endangered lagomorph. Between June 2006 and May 2008, we observed 60 adult radio-collared jackrabbits in Oaxaca, México. Tehuantepec jackrabbits exhibit breeding behaviors 250 days out of the year, with a high-intensity period during the rainy season (May–October). Females give birth to 2 leverets 32 days after copulation. Directly after birth, leverets are put into “beds” or “nests,” which are depressions in the ground covered by prairie grass ( Jouvea pilosa ). Females return to nurse and groom the leverets once per day until the leverets are weaned (12 days after birth). The breeding season and parental care behaviors of Tehuantepec jackrabbits are similar to those of other jackrabbits. Females produced an average of 2 litters per breeding season. The breeding rate for the Tehuantepec jackrabbit (4 leverets per breeding female per breeding season) is lower than the average of other species in the genus Lepus. The survival rate of Tehuantepec jackrabbit leverets (50% at day 19) is higher than that of other leporids. Predation by domestic dogs ( Canis familiaris ) is the main cause of mortality. Understanding reproductive behavior is critical for captive breeding, reintro duction, and conservation efforts for endangered leporids such as the Tehuantepec jackrabbit. Documentamos la fecha y la duración de cada fase de la reproducción, la tasa reproductiva, el amamantamiento, el cuidado parental y los instintos de supervivencia de los lebratos de la liebre de Tehuantepec ( Lepus flavigularis ), un lagomorfo en peligro crítico de extinción. Entre junio de 2006 y mayo de 2008 observamos 60 liebres adultas con collares radiotransmisores en Oaxaca, Mexico. Las liebres de Tehuantepec se reproducen 250 días del año, con un período de alta intensidad durante la estación lluviosa (de mayo a octubre). Las hembras paren 2 lebratos 32 días después de la cópula; colocan a los lebratos en “camas”, o huecos en el suelo cubiertos del pasto Jouvea pilosa, justo después de nacer. Las hembras regresan para amamantar y limpiar a los lebratos una vez cada tarde hasta destetarlos 12 días después de nacer. La temporada de reproducción y el cuidado parental de la liebre de Tehuantepec son parecidos a los de otras liebres. En promedio, las hembras producen 2 crías cada temporada de reproducción. La tasa de reproducción de la liebre de Tehuantepec (4 lebratos por hembra reproductora por temporada de reproducción) está por debajo del promedio de otras especies del género Lepus. La tasa de supervivencia de los lebratos de la liebre de Tehuantepec (50% al día 19) es superior a la que se ha documentado para otros lepóridos, siendo la principal causa de mortalidad la depredación por los perros domésticos ( Canis familiaris ). Es crucial entender el comportamiento reproductor para la crianza en cautiverio, la reintroducción y para los esfuerzos de conservación de lepóridos que están en peligro de extinción tal como occure con la liebre de Tehuantepec.     

Conservation status of the threatened, insular San Jose brush rabbit ( Sylvilagus mansuetus )

The conservation status and distribution of the insular endemic San Jose brush rabbit ( Sylvilagus mansuetus ), as well as threats to its population viability, were determined through surveys undertaken since 1995 on San José Island in the Gulf of California, Mexico. Sylvilagus mansuetus is restricted to a specific desert habitat found in the southwestern coastal plains of the island. Vegetation in this habitat is composed primarily of 7 plant species. The extent of rabbit occurrence is only 20 km 2 , and the population density estimate in the most optimal habitat is 25–35 individuals · km –2 . To our knowledge, the San Jose brush rabbit possesses the smallest distribution among all lagomorph species. Sylvilagus mansuetus is threatened by a population of feral cats and by human activities, including illegal hunting, development of a tourist area, and a salt mine. Human activities, even over a short time frame, could severely impact this restricted area and endanger the survival of this species. Recommended management includes removing cats and conducting additional research on the rabbit’s life history and ecology. Se determinó el estado de conservación y la distribución del conejo de San José ( Sylvilagus mansuetus ), una especie insular endémica, mediante muestreos que se han llevado a cabo desde 1995 en la isla de San José en el Mar de Cortés, México. Sylvilagus mansuetus quedó restringido a un tipo específico de hábitat desértico en la llanura costera suroccidental de la isla, donde predominan 7 especies de plantas. La extensión de la especie es de sólo 20 km 2 , y la densidad de la población en el hábitat óptimo se estimó entre 25 y 35 individuos · km –2 . Hasta donde conocemos, el conejo de San José tiene el área de distribución más pequeña de todas las especies de lagomorfos. Sylvilagus mansuetus se ve amenazado por una población de gatos ferales y por actividades humanas tales como la caza ilegal, el turismo y la operación de una mina de sal. Las actividades humanas podrían tener un impacto severo en esta área restringida y podrían poner en peligro la supervivencia de esta especie dentro de poco tiempo. Algunas acciones recomendables para el manejo de la especie incluyen el eliminar los gatos y llevar a cabo estudios adicionales para obtener más detalles sobre la biología y ecología del conejo a fin de mejorar su conservación.     

Status of an invading mainland jackrabbit on Cerralvo island, Gulf of California

We report the first observations of the black-tailed jackrabbit ( Lepus californicus ) on Cerralvo Island, Baja California Sur, Mexico. Evidence suggests a self-sustaining population. Analysis of available records indicates no previous record of Lepus on the island. Introduction of the jackrabbit to the island appears to have occurred between 1960 and 1991.     

基于遥感与区域化方法的无资料流域水文模型参数优化方法

针对无资料流域径流预报的难点, 探讨水文模型参数优化的共性问题, 综述区域化方法和遥感方法的研究现状。首先从水文模型参数优化面临的共性问题, 即水文地理数据生成、目标函数构建和优化方法选择等问题出发, 分析其对参数优选结果的影响, 并归纳出当前广泛认可的解决方案。然后结合区域化方法的技术原理和研究进展, 着重论述测站密度对区域化方法性能的影响, 并分析该方法在中国的适用性。接着从研究区域、水文模型结构、遥感资料以及率定目标等方面归纳总结遥感方法优化水文模型参数的最新研究进展。最后对区域化方法和遥感方法的优缺点及未来发展前景进行对比分析, 为中国无资料或缺资料流域径流预报实践提供参考。