The role of within-plant variation in nectar production: an experimental approach.

BACKGROUND AND AIMS: Nectar, a plant reward for pollinators, can be energetically expensive. Hence, a higher investment in nectar production can lead to reduced allocation to other vital functions and/or increased geitonogamous pollination. One possible strategy employed by plants to reduce these costs is to offer variable amounts of nectar among flowers within a plant, to manipulate pollinator behaviour. Using artificial flowers, we tested this hypothesis by examining how pollinator visitation responds to inter- and intra-plant variation in nectar production, assessing how these responses impact the energetic cost per visit. METHODS: We conducted a 2 × 2 factorial experiment using artificial flowers, with two levels of nectar investment (high and low sugar concentration) and two degrees of intra-plant variation in nectar concentration (coefficient of variation 0 and 20 %). The experimental plants were exposed to visits (number and type) from a captive Bombus impatiens colony, and we recorded the total visitation rate, distinguishing geitonogamous from exogamous visits. Additionally, we calculated two estimators of the energetic cost per visit and examined whether flowers with higher nectar concentrations (richer flowers) attracted more bumblebees. KEY RESULTS: Plants in the variable nectar production treatment (coefficient of variation 20 %) had a greater proportion of flowers visited by pollinators, with higher rates of total, geitonogamous and exogamous visitation, compared with plants with invariable nectar production. When assuming no nectar reabsorption, variable plants incurred a lower cost per visit compared with invariable plants. Moreover, highly rewarding flowers on variable plants had higher rates of pollination visits compared with flowers with few rewards. CONCLUSIONS: Intra-plant variation in nectar concentration can represent a mechanism for pollinator manipulation, enabling plants to decrease the energetic costs of the interaction while still ensuring consistent pollinator visitation. However, our findings did not provide support for the hypothesis that intra-plant variation in nectar concentration acts as a mechanism to avoid geitonogamy. Additionally, our results confirmed the hypothesis that increased visitation to variable plants is dependent on the presence of flowers with nectar concentration above the mean.

Complete labial fusion with vaginal constriction band presenting as incomplete voiding.

BACKGROUND: Labial adhesions are most commonly described in prepubertal girls. Only a few cases have been reported in postmenopausal women presenting with incomplete voiding. CASE: This report describes a case of a 51-year-old postmenopausal woman who presented with incomplete voiding and urinary incontinence. On examination, she had complete labial fusion and intraoperative findings of distal vaginal stenosis due to a constriction band. The patient was surgically treated with lysis of the labial fusion, posterior vaginal advancement flap with complete resolution of her urinary symptoms. CONCLUSION: In this report, we present a case of a postmenopausal patient with complete labial fusion, distal vaginal stenosis, and incomplete voiding who underwent successful surgical management with good anatomical results and complete resolution of urinary symptoms.

Expression of ICAM-1, TNF-alpha, NF kappa B, and MAP kinase in tubers of the tuberous sclerosis complex.

Individuals affected with tuberous sclerosis complex (TSC) develop cortical tubers characterized by disorganized cytoarchitecture and morphologically abnormal cell types, such as dysplastic neurons (DNs) and giant cells (GCs). As part of ongoing cDNA array analysis to study the molecular pathogenesis of tuber formation, we detected increased expression of intercellular adhesion molecule-1 (ICAM-1) mRNA, a cell adhesion molecule (CAM) that functions in cytokine signaling, in tubers. Western and immunohistochemical analyses revealed that ICAM-1 protein was selectively expressed in tubers, but was only minimally expressed in control cortex, adjacent nontuberal cortex, or in non-TSC focal cortical dysplasia. Increased expression of ICAM-1 was found in mice in which the Tsc1 gene was conditionally inactivated in astrocytes. Expression of molecules involved in ICAM-1 activation and cytokine signaling were increased in tubers, including tumor necrosis factor alpha (TNF-alpha), mitogen activated protein kinase (MAPK), and nuclear factor kappa B (NF-kappaB). Numerous CD68-immunoreactive macrophages were observed clustered around GCs further supporting an inflammatory response in tubers. Expression of caspase 8 and Fas support cytokine activation and detection of TUNEL reactivity suggests ongoing cell death in tubers. Specific alterations in ICAM-1, TNF-alpha, NF-kappaB1, and MAPK expression coupled with the detection of numerous CD68-immunoreactive macrophages suggests activation of proinflammatory cytokine signaling pathways in tubers that may culminate in cell death.

Markers of cellular proliferation are expressed in cortical tubers.

p34cdc2, collapsin response mediator protein 4 (CRMP4), doublecortin (DCX), HuD, and NeuN expression was assessed in tuber (n = 16) and subependymal giant cell astrocytoma (SEGA; n = 6) specimens in tuberous sclerosis complex to define the developmental phenotype and lineage of giant cells (CGs) in these lesions. Many GCs exhibited HuD and NeuN immunolabeling suggesting a differentiated neural phenotype. Giant cells in tubers, SEGAs and subependymal nodules in the Eker rat model of TSC expressed CRMP4 and DCX. Tubers and SEGAs exhibit a heterogeneous profile of differentiation and may share a common cellular lineage. Tubers may contain a subpopulation of newly generated cells.