Pollen selection

In recent years a large number of reports have been published hinting about the possible role of selection at the male gametophyte level in natural conditions and its possible use as a tool in plant breeding programs. In this work, the evidence that has so far emerged on gametophytic selection is reviewed, and its relationship to pollen competition under natural conditions is analyzed. Information supporting an overlap in the genetic expression between the gametophytic and sporophytic phases is also reported, mainly in terms of isozymes and RNA hybridization. The correspondence between both phases is reviewed through their common response to different external agents such as temperature, salinity, metals, herbicides, fungal toxins, and other factors. Finally, the implications that pollen selection may have in plant breeding are evaluatedWe also acknowledge the U.S.-Spain Joint Committee for Scientific and Technological Cooperation and INIA for financial support.Peer reviewe

The diversity of neuronal phenotypes in rodent and human autonomic ganglia

Selective sympathetic and parasympathetic pathways that act on target organs represent the terminal actors in the neurobiology of homeostasis and often become compromised during a range of neurodegenerative and traumatic disorders. Here, we delineate several neurotransmitter and neuromodulator phenotypes found in diverse parasympathetic and sympathetic ganglia in humans and rodent species. The comparative approach reveals evolutionarily conserved and non-conserved phenotypic marker constellations. A developmental analysis examining the acquisition of selected neurotransmitter properties has provided a detailed, but still incomplete, understanding of the origins of a set of noradrenergic and cholinergic sympathetic neuron populations, found in the cervical and trunk region. A corresponding analysis examining cholinergic and nitrergic parasympathetic neurons in the head, and a range of pelvic neuron populations, with noradrenergic, cholinergic, nitrergic, and mixed transmitter phenotypes, remains open. Of particular interest are the molecular mechanisms and nuclear processes that are responsible for the correlated expression of the various genes required to achieve the noradrenergic phenotype, the segregation of cholinergic locus gene expression, and the regulation of genes that are necessary to generate a nitrergic phenotype. Unraveling the neuron population-specific expression of adhesion molecules, which are involved in axonal outgrowth, pathway selection, and synaptic organization, will advance the study of target-selective autonomic pathway generation