Arabidopsis AGC3 kinases and PIN plasma membrane abundance

The plant hormone auxin plays a central role in the growth and development of plants. Auxin acts in a concentration dependent manner and polar cell-to-cell transport of this hormone determines its distribution in the tissues of plants. This polar auxin transport is mediated by several families of auxin transporters, including the PIN FORMED (PIN) auxin efflux carriers that determine the direction of transport by their polar localization at the plasma membrane. The plasma membrane abundance and polarity of PINs (and thereby of polar auxin transport) is regulated by their post-translational modification, of which phosphorylation is best studied. PIN proteins in Arabidopsis consist of two transmembrane domains separated by a ‘long’ (PIN1,2,3,4,6,7) or by a ‘short’ (PIN5,8) hydrophilic loop. Phosphorylation of ‘long’ PINs in their central hydrophilic loop by the AGC3 kinases PINOID, WAG1 and WAG2 triggers shootward (apical) or outer-lateral polarity. The AGC1- type D6 kinases also phosphorylate the PIN hydrophilic loop, however this was reported to result in auxin transport activation rather than subcellular polarity establishment. Here we investigate the conservation and phylogeny of AGC3 and D6 kinases and their phosphorylation sites in PINs from the earliest land plants to flowering plants. In early land plants, many of the same proteins and conserved motifs can be found, however it is in monocots and dicots that conservation of PIN phosphorylation by AGC3 and D6 kinases is strongest. The expansion and increased conservation of AGC3 and D6 kinases and PINs in later lineages such as monocot and dicot flowering plants, is in line with their important role in the formation of reproductive organs and in the tropic growth responses that allow plants to adapt to changes in their environment.Plant science

Location Matters: Canopy Light Responses over Spatial Scales

Plants use light as a signal to determine neighbour proximity in dense vegetation. Far-red (FR) light reflected from neighbour plants elicits an array of growth responses throughout the plant. Recently, various light quality-induced signals have been discovered that travel between organs and tissue layers. These signals share upstream and downstream components, but can have opposing effects on cell growth. The question is how plants can coordinate these spatial signals into various growth responses in remote tissues. This coordination allows plants to adapt to the environment, and understanding the underlying mechanisms could allow precision engineering of crops. To achieve this understanding, plant photobiology research will need to focus increasingly on spatial signalling at the whole-plant level

Transition to parenthood and quality of parenting among gay, lesbian and heterosexual couples who conceived through assisted reproduction

Little research has focused on the emotions felt during pregnancy and early parenthood as well as the initial quality of parenting displayed by first-time parents who conceived using assisted reproduction technologies (surrogacy, donor insemination, and in vitro fertilization). Research on primary and secondary caregivers in gay, lesbian, and heterosexual families is especially sparse. The current study examined 35 gay-father families, 58 lesbian-mother families and 41 heterosexual-parent families with their infants. Families were assessed at home when their infants were 4 months old (±14 days), and each parent participated in an audio-recorded standardized semi-structured interview in which we explored parental feelings during pregnancy, feelings about the parental role, perceived parental competence, the enjoyment of parenthood, expressed warmth and emotional over-involvement of parents. 13 Heterosexual parents reported less positive feelings in early pregnancy than lesbian parents, while gay parents reported less positive feelings at the end of pregnancy than lesbian mothers and more positive feelings about parenthood during the first post-partum weeks than heterosexual parents. There was no interaction between family type and caregiver role on reported feelings, or on perceived competence, enjoyment, warmth, and involvement. The present findings elucidate the transition to parenthood among first-time parents conceiving through assisted reproductive technologies, and especially contribute to our knowledge about gay fathers who became parents through surrogacy

Edge States of Monolayer and Bilayer Graphene Nanoribbons

On the basis of tight-binding lattice model, the edge states of monolayer and bilayer graphene nanoribbons (GNRs) with different edge terminations are studied. The effects of edge-hopping modulation, spin-orbital coupling (SOC), and bias voltage on bilayer GNRs are discussed. We observe the following: (i) Some new extra edge states can be created by edge-hopping modulation for monolayer GNRs. (ii) Intralayer Rashba SOC plays a role in depressing the band energy gap $E_g$ opened by intrinsic SOC for both monolayer and bilayer GNRs. An almost linear dependent relation, i.e., $E_g\sim \lambda_R$, is found. (iii) Although the bias voltage favors a bulk energy gap for bilayer graphene without intrinsic SOC, it tends to reduce the gap induced by intrinsic SOC. (iv) The topological phase of the quantum spin Hall effect can be destroyed completely by interlayer Rashba SOC for bilayer GNRs.Comment: 6 pages, 6 figure

An INDEHISCENT-controlled auxin response specifies the separation layer in early Arabidopsis fruit

Plant science