The 'neighbour effect' and its role in shaping the positional pattern of seed development in fruits: An illustration from the pods of Erythrina suberosa

Plants exhibit certain intra-fruit positional patterns in the development of seeds. These patterns have been generally interpreted to be a consequence of resource and fertilization gradients. However, such positional patterns might also be shaped by the 'neighbour effect', wherein formation and development of a seed at any position might positively or negatively influence those of other seeds in the neighbourhood. In this article, we examine the role of such neighbour effect in shaping the positional pattern of seeds in the pods of Erythrina suberosa. The results suggest the existence of a positive neighbour effect leading to a higher frequency of seeds in contiguous positions.

Use of a specific aromatase inhibitor for determining whether there is a role for oestrogen in follicle/oocyte maturation, ovulation and preimplantation embryo development

The specific role of oestrogen in follicular maturation, ovulation and early embryonic development was investigated using Fadrozole (CGS 16949A), a non-steroidal aromatase inhibitor, to block oestrogen synthesis specifically and effectively in experimental animals. Induced and normal cyclical follicular maturation as well as normal and hCG/LH-induced ovulation were relatively unaffected by significantly depleting oestrogen in all animals (hamsters, rabbits, monkeys) studied other than rats. Fadrozole treatment significantly reduced the number of healthy antral follicles produced and the ovulatory response to exogenous hCG of immature rats primed with pregnant mares' serum gonadotrophin. The effect was specific, in that exogenously administered oestrogen reversed the blockade. Depletion of oestrogen, starting early in pro-oestrus in hamsters, had no effect on ovulation, oocyte maturation and fertilization, as normal implantation sites were seen on day 6 after coitus. In rabbits, oestrogen depletion during the periovulatory phase affected oviductal morphology and function. Although fertilization was not impaired, early embryo development did not appear to be normal. In monkeys, oestrogen depletion during the follicular phase did not lead to a block of follicular maturation or ovulation but resulted in a significant reduction in secretion of cervical mucus. Administration of either Fadrozole or Tamoxifen during the early luteal phase in cyclic monkeys that were allowed to mate prevented implantation and this appears to be due to impaired fertilization or faulty embryo development. These results suggest that, although there is a clear requirement for oestrogen to support the reproductive cycle in the female, the need for oestrogen in regulating specific events is species dependent.

Trends and Variability of AVHRR-Derived NPP in India

In this paper, we estimate the trends and variability in Advanced Very High Resolution Radiometer (AVHRR)-derived terrestrial net primary productivity (NPP) over India for the period 1982-2006. We find an increasing trend of 3.9% per decade (r = 0.78, R-2 = 0.61) during the analysis period. A multivariate linear regression of NPP with temperature, precipitation, atmospheric CO2 concentration, soil water and surface solar radiation (r = 0.80, R-2 = 0.65) indicates that the increasing trend is partly driven by increasing atmospheric CO2 concentration and the consequent CO2 fertilization of the ecosystems. However, human interventions may have also played a key role in the NPP increase: non-forest NPP growth is largely driven by increases in irrigated area and fertilizer use, while forest NPP is influenced by plantation and forest conservation programs. A similar multivariate regression of interannual NPP anomalies with temperature, precipitation, soil water, solar radiation and CO2 anomalies suggests that the interannual variability in NPP is primarily driven by precipitation and temperature variability. Mean seasonal NPP is largest during post-monsoon and lowest during the pre-monsoon period, thereby indicating the importance of soil moisture for vegetation productivity.

An estimate of equilibrium sensitivity of global terrestrial carbon cycle using NCAR CCSM4

Increasing concentrations of atmospheric CO2 influence climate, terrestrial biosphere productivity and ecosystem carbon storage through its radiative, physiological and fertilization effects. In this paper, we quantify these effects for a doubling of CO2 using a low resolution configuration of the coupled model NCAR CCSM4. In contrast to previous coupled climate-carbon modeling studies, we focus on the near-equilibrium response of the terrestrial carbon cycle. For a doubling of CO2, the radiative effect on the physical climate system causes global mean surface air temperature to increase by 2.14 K, whereas the physiological and fertilization on the land biosphere effects cause a warming of 0.22 K, suggesting that these later effects increase global warming by about 10 % as found in many recent studies. The CO2-fertilization leads to total ecosystem carbon gain of 371 Gt-C (28 %) while the radiative effect causes a loss of 131 Gt-C (10 %) indicating that climate warming damps the fertilization-induced carbon uptake over land. Our model-based estimate for the maximum potential terrestrial carbon uptake resulting from a doubling of atmospheric CO2 concentration (285-570 ppm) is only 242 Gt-C. This highlights the limited storage capacity of the terrestrial carbon reservoir. We also find that the terrestrial carbon storage sensitivity to changes in CO2 and temperature have been estimated to be lower in previous transient simulations because of lags in the climate-carbon system. Our model simulations indicate that the time scale of terrestrial carbon cycle response is greater than 500 years for CO2-fertilization and about 200 years for temperature perturbations. We also find that dynamic changes in vegetation amplify the terrestrial carbon storage sensitivity relative to a static vegetation case: because of changes in tree cover, changes in total ecosystem carbon for CO2-direct and climate effects are amplified by 88 and 72 %, respectively, in simulations with dynamic vegetation when compared to static vegetation simulations.

Nitrogen deposition: how important is it for global terrestrial carbon uptake?

Global carbon budget studies indicate that the terrestrial ecosystems have remained a large sink for carbon despite widespread deforestation activities. CO2 fertilization, N deposition and re-growth of mid-latitude forests are believed to be key drivers for land carbon uptake. In this study, we assess the importance of N deposition by performing idealized near-equilibrium simulations using the Community Land Model 4.0 (CLM4). In our equilibrium simulations, only 12-17% of the deposited nitrogen is assimilated into the ecosystem and the corresponding carbon uptake can be inferred from a C : N ratio of 20 : 1. We calculate the sensitivity of the terrestrial biosphere for CO2 fertilization, climate warming and N deposition as changes in total ecosystem carbon for unit changes in global mean atmospheric CO2 concentration, global mean temperature and Tera grams of nitrogen deposition per year, respectively. Based on these sensitivities, it is estimated that about 242 PgC could have been taken up by land due to the CO2 fertilization effect and an additional 175 PgC taken up as a result of the increased N deposition since the pre-industrial period. Because of climate warming, the terrestrial ecosystem could have lost about 152 PgC during the same period. Therefore, since pre-industrial times terrestrial carbon losses due to warming may have been more or less compensated by effects of increased N deposition, whereas the effect of CO2 fertilization is approximately indicative of the current increase in terrestrial carbon stock. Our simulations also suggest that the sensitivity of carbon storage to increased N deposition decreases beyond current levels, indicating that climate warming effects on carbon storage may overwhelm N deposition effects in the future.

Vermicompost reduces the invasiveness of the earthworm species Dichogaster bolaui compared to the use of compost in a degraded tropical soil in Northern Vietnam

In Northern Vietnam, organic fertilization programmes are being tested to restore soil fertility and reduce soil erosion. However, the amendment of organic matter in soil is also associated with the development of the invasive earthworm species Dichogaster bolaui. The objective of this study was to investigate the influence of organic matter amendment quality (compost vs. vermicompost) on D. bolaui. Our study confirmed D. bolaui development in organic patches in the field. However, we also observed that the flat-backed millipede Asiomorpha coarctata proliferated in these organic patches. Native to Asia, this millipede species is also considered as invasive in America. Both D. bolaui and A. coarctata more rapidly colonized compost than vermicompost patches. A laboratory experiment confirmed this trend and showed the limited development of D. bolaui in vermicompost. This is probably because of the decreased palatability of this substrate to soil fauna. In conclusion, any restoration practice that aims to increase the organic stocks in soils degraded by erosion should consider the quality of the organic amendment. In Northern Vietnam, vermicompost may be the preferred substrate for restoring soils while limiting the spread of D. bolaui. (C) 2014 Elsevier Masson SAS. All rights reserved.

Modeling of solar radiation management: a comparison of simulations using reduced solar constant and stratospheric sulphate aerosols

The climatic effects of Solar Radiation Management (SRM) geoengineering have been often modeled by simply reducing the solar constant. This is most likely valid only for space sunshades and not for atmosphere and surface based SRM methods. In this study, a global climate model is used to evaluate the differences in the climate response to SRM by uniform solar constant reduction and stratospheric aerosols. Our analysis shows that when global mean warming from a doubling of CO2 is nearly cancelled by both these methods, they are similar when important surface and tropospheric climate variables are considered. However, a difference of 1 K in the global mean stratospheric (61-9.8 hPa) temperature is simulated between the two SRM methods. Further, while the global mean surface diffuse radiation increases by similar to 23 % and direct radiation decreases by about 9 % in the case of sulphate aerosol SRM method, both direct and diffuse radiation decrease by similar fractional amounts (similar to 1.0 %) when solar constant is reduced. When CO2 fertilization effects from elevated CO2 concentration levels are removed, the contribution from shaded leaves to gross primary productivity (GPP) increases by 1.8 % in aerosol SRM because of increased diffuse light. However, this increase is almost offset by a 15.2 % decline in sunlit contribution due to reduced direct light. Overall both the SRM simulations show similar decrease in GPP (similar to 8 %) and net primary productivity (similar to 3 %). Based on our results we conclude that the climate states produced by a reduction in solar constant and addition of aerosols into the stratosphere can be considered almost similar except for two important aspects: stratospheric temperature change and the consequent implications for the dynamics and the chemistry of the stratosphere and the partitioning of direct versus diffuse radiation reaching the surface. Further, the likely dependence of global hydrological cycle response on aerosol particle size and the latitudinal and height distribution of aerosols is discussed.

A quantitative imaging-based screen reveals the exocyst as a network hub connecting endocytosis and exocytosis

The coupling of endocytosis and exocytosis underlies fundamental biological processes ranging from fertilization to neuronal activity and cellular polarity. However, the mechanisms governing the spatial organization of endocytosis and exocytosis require clarification. Using a quantitative imaging-based screen in budding yeast, we identified 89 mutants displaying defects in the localization of either one or both pathways. High-resolution single-vesicle tracking revealed that the endocytic and exocytic mutants she4 Delta and bud6 Delta alter post-Golgi vesicle dynamics in opposite ways. The endocytic and exocytic pathways display strong interdependence during polarity establishment while being more independent during polarity maintenance. Systems analysis identified the exocyst complex as a key network hub, rich in genetic interactions with endocytic and exocytic components. Exocyst mutants displayed altered endocytic and post-Golgi vesicle dynamics and interspersed endocytic and exocytic domains compared with control cells. These data are consistent with an important role for the exocyst in coordinating endocytosis and exocytosis.

Meiosis in flowering plants and other green organisms.

Sexual eukaryotes generate gametes using a specialized cell division called meiosis that serves both to halve the number of chromosomes and to reshuffle genetic variation present in the parent. The nature and mechanism of the meiotic cell division in plants and its effect on genetic variation are reviewed here. As flowers are the site of meiosis and fertilization in angiosperms, meiotic control will be considered within this developmental context. Finally, we review what is known about the control of meiosis in green algae and non-flowering land plants and discuss evolutionary transitions relating to meiosis that have occurred in the lineages giving rise to the angiosperms.

Impacto social y legislativo del Informe Warnock : consecuencias de una visión utilitarista del embrión

El presente trabajo surge del análisis del Informe Warnock y muestra cómo el Informe influyó en diferentes legislaciones, al tiempo que describe su impacto y la nueva forma de ver y conocer, a partir de éste, ciertos temas por parte del ciudadano común. Se analizará cada uno de los temas, por demás controvertidos, planteados en el Informe, entre los que se pueden enumerar los siguientes: inicio de la vida humana, tratamientos de fertilización asistida, donantes anónimos, criopreservación de embriones y alquiler de vientres. El Informe Warnock fue tomado como referencia para la redacción de distintas normas legales en todo el mundo. De allí su trascendencia, que marca hasta hoy un antes y un después en la sociedad científica en general y en la sociedad civil en particular.

Cuatro cuestiones sobre la regulación de las técnicas de fecundación artificial en el provecto de Código Civil 2012

Resumen: El presente artículo analiza el tema de las técnicas de fecundación artificial en el proyecto de nuevo Código Civil y Comercial presentado en el Congreso Argentino en el año 2012. Considera que el proyecto sólo regula algunos efectos filiatorios y soslaya importantes cuestiones que son decisivas a la luz de la dignidad de la persona humana y sus derechos fundamentales. En concreto, se analizan críticamente cuatro presupuestos o cuestiones previas que condicionan la regulación jurídica del tema, a saber: a) La autorización o no de las técnicas de fecundación artificial; b) La cuestión del comienzo de la existencia de la persona humana; c) La autorización de la dación de gametos con fines reproductivos; d) La voluntad procreacional y la determinación de la filiación.

Raíces ideológicas de la perspectiva de género

Resumen: El feminismo radical o de género tiene sus orígenes históricos, su matriz ideológica y su modo dialéctico de entender la relación varón-mujer, en el pensamiento marxista (Engels, de Beauvoir, Firestone). La “antítesis” de esta lucha de sexos es la revolución feminista radical, y su principal instrumento revolucionario y de penetración cultural es la ideología de género. La fase central de esta revolución es el apoderamiento, por parte de las mujeres, de los medios de reproducción. Los medios que han demostrado ser más aptos para lograr la victoria son el aborto por decisión privativa de la mujer, la fecundación artificial y el matrimonio entre personas del mismo sexo. La revolución se libra en el campo cultural y, luego, en el jurídico.

Evaluación de técnicas de defensa y de la densidad en el cultivo de una nueva hortaliza : Cucúrbita pepo var. vegetable spaghetti

El zapallo Spaghetti, cultivo vigoroso de clima templado, constituye una alternativa productiva interesante y novedosa para nuestro país. El objetivo de este estudio fue evaluar el efecto del mulching y de la densidad sobre el rendimiento total, el peso medio y el calibre de los frutos. El estudio se llevó a cabo en Azul sobre un suelo Argiudol típico en camellones de 0,80 m de ancho con diferentes densidades de siembra. Se realizó una fertilización profunda en bandas de 0,80 m con fosfato diamónico, controlando las malezas en forma química, manual y mecánicamente, y las plagas haciendo aplicaciones preventivas de insecticidas y fungicidas. La siembra manual se efectuó el 2 de noviembre y los tratamientos fueron: densidades de siembra de 20, 15, 10 y 5 mil pl/ha (D1, D2, D3 y D4), con y sin mulching. Se trabajó con 32 parcelas y cada una tenía tres surcos de seis metros de longitud separados entre si por 2m. Se realizaron cuatro cosechas al llegar a la madurez completa (15/2, 29/2, 7/3 y 3/4). Los calibres evaluados fueron: (1) 2,2 kg, (2) 1,7 kg; (3) 1,3 kg y (4) 0,8 kg / fruto. Para el análisis de los datos se utilizó un modelo de bloques completamente aleatorizados con parcelas sub-divididas. En la parcela principal se evaluó el efecto del mulching, en la subparcela la densidad y la interacción de mulching por densidad, y en la subsubparcelas las diferentes cosechas. La cosecha total mostró diferencias significativas para el efecto del mulching, obteniéndose 71,90 t/ha (a) (con mulching) y 62,02 t/ha (b) (sin mulching); para cada densidad se detectaron diferencias significativas para el efecto mulching: D1: 84,45 t/ha (a), D2: 76,47 t/ha (ab); D3: 65,14 t/ha (b) y D4: 61,55 t/ha (b). Se observaron diferencias significativas en el número de frutos cosechados: con mulching (51.667 frutos/ha) y sin mulching (44.167 frutos/ha), y para las diferentes densidades: D1: 54.167 (a); D2: 50.000 (ab); D3: 47.700 (ab) y D4: 40.833 (b) t/ha. La composición de calibres de frutos cosechados fue el mismo para todos los tratamientos y cosechas.

El caso Artavia Murillo y otros vs. Costa Rica (fecundación in vitro) : la redefinición del derecho a la vida desde la concepción, reconocido en la Convención Americana

Resumen: El Artículo 4(1) de la Convención Americana protege la vida de la persona por nacer desde el momento de la concepción. Esta nota analiza críticamente la interpretación restrictiva de este artículo realizada por la Corte Interamericana de Derechos Humanos en el caso Artavia Murillo y otros vs. Costa Rica, sobre la prohibición de la fecundación in vitro en ese país. La nota describe cómo la Corte revirtió parcialmente el reconocimiento del derecho a la vida del niño no nacido, qué hicieron los Estados latinoamericanos, al adoptar la Convención Americana, a través de una aplicación distorsionada de sus propias técnicas de interpretación y de las normas internacionales de interpretación de los tratados.

El concepto de “vida privada” en la fecundación heteróloga y el diagnóstico genético preimplantatorio : a propósito de la STEDH “Costa y Pavan c/Italia, del 28 de agosto de 2012

Resumen: Esta ocasión me brinda la oportunidad de realizar algo más que un mero comentario a la Sentencia del Tribunal Europeo de Derechos Humanos (TEDH), “Costa y Pavan c/ Italia”. Es decir, voy a esbozar una toma de postura prescriptiva contraria a la filosofía individualista de fondo del TEDH respecto al presente caso, en base a un discurso jurídico-filosófico. La frivolidad del TEDH a la hora de tratar algunos temas de bioética y bioderecho se enmarca en el uso de un lenguaje políticamente correcto y de cierto consenso pragmático, recubierto en ocasiones de ropajes jurídico-formales, en lo concerniente al amplio artículo 8º del CEDH. Cuestiones vitales en la configuración de la realidad humana que deben tratarse desde una óptica comprometida con uno mismo y con el tiempo que le ha tocado vivir. Con semejante punto de vista resulta clave otorgar a las palabras un contenido, pero sobre ello siempre subyace el miedo a que las palabras acaben diciendo lo que nosotros queramos que digan. En el ámbito jurídico, en ocasiones, ese nosotros puede ser asumido por algún alto tribunal.