Biomedical subjects

Nicola Illing

Publications and source records attributed to Nicola Illing.

6 recordsLinked to original sources

PubMed2026

Supergene control of chiral development in mirror-image flowers.

How genes determine the development of chiral structures is a fascinating question. The reciprocal placement of female and male organs on opposite sides of mirror-image flowers promotes efficient cross-pollination. Here, we identified that in butterfly lilies, female and male organs deflect by a combination of genetically controlled chirality and gravitropism, orienting left and right with respect to an external rather than internal reference axis. We found coordinated organ placement to be controlled by a hemizygous supergene containing two candidate causal loci, MIR156-R and YUCCA-R, that are responsible for opposite female and male organ orientation, respectively. The resulting differential placement of pollen carrying the two supergene alleles on pollinators' bodies leads to their transfer to the stigmas of flowers with opposite handedness and maintenance of the reproductive polymorphism.

Alleles↗

PubMed2006

A brain-behaviour initiative for South Africa: the time is right.

BACKGROUND: Many have advocated for science and health research in developing world settings. However, there has been less focus on the value of basic and clinical neuroscience research in this context. The current paper focuses on the relevance of a brain-behaviour research initiative in South Africa. METHODS: Workshops sponsored by the University of Cape Town Research Office and by the National Research Foundation have recently focused on the state of South African basic and clinical neuroscience, and on how to strengthen research in these areas. The context of the discussion included national science and health priorities, as well as local research opportunities. RESULTS: Neuropsychiatric disorders account for the second largest proportion of the burden of disease in South Africa, but receive relatively little research funding. There is a critical need for research, and there are unique research opportunities, in areas such as trauma and resilience, impulsive behaviour (eg violence, sexual risk taking, and substance abuse), and neuroAIDS. Basic, clinical, and systems research can all make important contributions. CONCLUSION: There is a need to apprise policy-makers in developing world countries such as South Africa of the need for increased expenditure on basic and clinical neuroscience research. Local and international collaboration may be useful in increasing research capacity in South Africa, and ultimately in improving mental health services.

Mental Health↗

PubMed2003

Photosynthetic genes are differentially transcribed during the dehydration-rehydration cycle in the resurrection plant, Xerophyta humilis.

One of the desiccation-tolerant mechanisms of the resurrection plant, Xerophyta humilis, is the ability to shut down photosynthesis reversibly. The X. humilis psbR and ChlP genes, encoding the 10 kDa polypeptide of photosystem II (PSII) and a geranylgeranyl reductase, respectively, were isolated in a differential display screen as dehydration-down-regulated and rehydration-up-regulated transcripts. Two other PSII genes, psbA (chloroplast-encoded) and psbP (nuclear-encoded), isolated by degenerate primer PCR, display a similar trend in expression.

Acclimatization↗

PubMed2003

Differential brain distribution of gonadotropin-releasing hormone receptors in the goldfish.

The present study describes the differential distributions in the brain of the two goldfish gonadotropin-releasing hormone (GnRH) receptors, using both immunohistochemistry and in situ hybridization approaches. The goldfish GnRH GfA and GfB receptors are variant forms of the same receptor subtype, although with distinct differences in ligand binding characteristics, and differential distributions in the pituitary and body tissues [Proc. Natl. Acad. Sci. USA 96 (1999) 2526]. The goldfish GnRH GfA receptor was found to be widespread throughout the brain, with neurons showing immunoreactivity in the olfactory bulbs, telencephalon, preoptic region, ventro-basal hypothalamus, thalamus, midbrain, motor neurons of the fifth, seventh, and tenth cranial nerves, reticular formation, cerebellum, and motor zone of the vagal lobes. The tracts in the posterior commissure, optic tectum, and motor zone of the vagal lobes also demonstrated immunoreactivity. While the brain was not systematically surveyed for in situ hybridization, hybridization was found in similar locations in the telencephalon, preoptic region, ventro-basal hypothalamus, cerebellum, and optic tectum. Hybridization was additionally found in the medial hypothalamus. The goldfish GnRH GfB receptor was found to have a more restricted distribution in the brain, with neurons showing immunoreactivity in the telencephalon, preoptic region, and ventro-basal hypothalamus. In situ hybridization demonstrated a somewhat wider distribution of expression of the receptor, with hybridization occurring in the preoptic region, ventro-basal and medial hypothalamus, as well as in the thalamus, epithalamus, and optic tectum. The widespread distribution of GnRH GfA receptor, and in particular its localization in the midbrain tegmentum in the region of the GnRH-II neurons, suggests that this receptor may be involved in the behavioral actions of GnRH peptides in the goldfish.

Animals↗

PubMed2002

Conditionally immortalized clonal cell lines from the mouse olfactory placode differentiate into olfactory receptor neurons.

To test extracellular signals that direct the development of the olfactory system, we have generated clonal temperature-sensitive cell lines that represent distinct cellular lineages derived from the E10 mouse olfactory placode. Two of these lines, OP6 and OP27, express (at the permissive temperature), a transcriptional profile representing intermediate-late developmental stages in the olfactory receptor neuron (ORN) lineage. At the nonpermissive temperature, both OP6 and OP27 cells can be induced by all-trans retinoic acid to differentiate into a population of mature bipolar ORN-like cells. In response to retinoic acid, differentiated OP6 and OP27 down-regulate neuron-specific transcription factors required for early stages of neuronal differentiation, and shift active components of the neurotrophin signaling cascade (Trk receptors) into a kinase inactive state. When morphologically mature, OP6 and OP27 express the mature ORN chemosensory signaling components, olfactory G-protein (G(olf)), Type III adenylate cyclase (ACIII), OCNC1, and the olfactory marker protein (OMP). OP27 expresses one odorant receptor, OR 27-3. OP6 expresses two very closely related receptors, OR 6-13 and OR 6-8. Voltage-gated sodium and potassium channels resembling those recorded from primary cultures of ORNs can also be recorded from a subset of differentiated OP6 cells.

Animals↗

PubMed2002

Two mutations in extracellular loop 2 of the human GnRH receptor convert an antagonist to an agonist.

GnRH regulates the reproductive system through cognate G protein-coupled receptors in vertebrates. Certain GnRH analogs that are antagonists at mammalian receptors behave as agonists at Xenopus laevis and chicken receptors. This phenomenon provides the opportunity to elucidate interactions and the mechanism underlying receptor activation. A D-Lys(iPr) in position 6 of the mammalian GnRH receptor antagonist is required for this agonist activity (inositol phosphate production) in the chicken and X. laevis GnRH receptors. Chimeric receptors, in which extracellular loop domains of the human GnRH receptor were substituted with the equivalent domains of the X. laevis GnRH receptor, identified extracellular loop 2 as the determinant for agonist activity of one of the mammalian antagonists: antagonist 135-18. Site-directed mutagenesis of nine nonconserved residues in the C-terminal domain of extracellular loop 2 of the human GnRH receptor showed that a minimum of two mutations (Val(5.24(197))Ala and Trp(5.32(205))His) is needed in this region for agonist activity of antagonist 135-18. Agonist activity of antagonist 135-18 was markedly decreased by low pH (<7.0) compared with GnRH agonists. These findings indicate that D-Lys(iPr)(6) forms a charge-supported hydrogen bond with His(5.32(205)) to stabilize the receptor in the active conformation. This discovery highlights the importance of EL-2 in ligand binding and receptor activation in G protein-coupled receptors.

Amino Acid Sequence↗