Biophysical Characterization of Diacylglycerol Pyrophosphate

Diacylglycerol pyrophosphate (DGPP), a phosphorylated form of phosphatidic acid (PA), gained attention due to its role as a signaling lipid. In plants, DGPP is virtually absent in non-stimulated cells but its concentration increases in response to various stress stimuli. It is yet unclear what its molecular function is and how it exerts its effects. To help characterize the functions of PA and DGPP, this study examined the lipids in pH 4 through 11 by infrared spectroscopy, and found that the pure DOPA multilamellar vesicles deprotonate to the PO32- species at lower pH than pure DGPP multilamellar vesicles, which is different than what has been found in previous studies. This study elucidated the ionization state and stretching frequencies of each lipid over the physiological pH range

WaSHUp: Innovating Water Sanitation and Hygiene Upgrading in Langrug

The current top-down, subsidized, government approach to water, sanitation, and hygiene (WaSH) provision in South Africa has not been successful. The goal of this project was to establish a framework for the development of innovative, multi-stakeholder, multipurpose, and community- driven WaSH alternatives in Langrug, an informal settlement in the Stellenbosch Municipality. In collaboration with local co-researchers, government and NGO partners, we developed a process for incremental upgrading, constructed an innovative tap, implemented paintings to foster early childhood development in an ablution block, and proposed designs for a future multipurpose hall. The work created a starting point for Langrug to become a centre for global learning and research in WaSH provision

Health Clinics - Saving Two Birds with One Stone

The amount of cases of malnutrition and HIV/AIDS in Nigeria must be reduced

Electrophysiological properties and projections of lateral hypothalamic parvalbumin positive neurons.

Cracking the cytoarchitectural organization, activity patterns, and neurotransmitter nature of genetically-distinct cell types in the lateral hypothalamus (LH) is fundamental to develop a mechanistic understanding of how activity dynamics within this brain region are generated and operate together through synaptic connections to regulate circuit function. However, the precise mechanisms through which LH circuits orchestrate such dynamics have remained elusive due to the heterogeneity of the intermingled and functionally distinct cell types in this brain region. Here we reveal that a cell type in the mouse LH identified by the expression of the calcium-binding protein parvalbumin (PVALB; LHPV) is fast-spiking, releases the excitatory neurotransmitter glutamate, and sends long range projections throughout the brain. Thus, our findings challenge long-standing concepts that define neurons with a fast-spiking phenotype as exclusively GABAergic. Furthermore, we provide for the first time a detailed characterization of the electrophysiological properties of these neurons. Our work identifies LHPV neurons as a novel functional component within the LH glutamatergic circuitry

Activation of a lateral hypothalamic-ventral tegmental circuit gates motivation.

Across species, motivated states such as food-seeking and consumption are essential for survival. The lateral hypothalamus (LH) is known to play a fundamental role in regulating feeding and reward-related behaviors. However, the contributions of neuronal subpopulations in the LH have not been thoroughly identified. Here we examine how lateral hypothalamic leptin receptor-expressing (LHLEPR) neurons, a subset of GABAergic cells, regulate motivation in mice. We find that LHLEPR neuronal activation significantly increases progressive ratio (PR) performance, while inhibition decreases responding. Moreover, we mapped LHLEPR axonal projections and demonstrated that they target the ventral tegmental area (VTA), form functional inhibitory synapses with non-dopaminergic VTA neurons, and their activation promotes motivation for food. Finally, we find that LHLEPR neurons also regulate motivation to obtain water, suggesting that they may play a generalized role in motivation. Together, these results identify LHLEPR neurons as modulators within a hypothalamic-ventral tegmental circuit that gates motivation

Electrophysiological properties of LH^PV neurons.

<p>Electrophysiological properties of LH^PV neurons.</p

LH^PV neurons exhibit fast-spiking characteristics.

<p>(A) Immunohistochemical identification of parvalbumin-expressing neurons in a horizontal section of the mouse LH. Dotted lines highlight a cluster of immuno-positive LH^PV neurons (green). Scale bar, 200 μm. (B) Representative traces and firing pattern of a fast-spiking LH^PV neuron in response to step hyperpolarizing (bottom traces; from −100 to 0 pA) and depolarizing current injections (upper traces; 900 pA) during a 500 ms pulse. Resting membrane potential (V_rmp = −66 mV) and maximal firing frequency 264 Hz. Abbreviations, fornix (f), optic tract (opt), lateral mammillary nucleus (LM), lateral (L), medial (M), rostral (R), and caudal (C).</p

Molecular and electrophysiological characterization of LH^PV neurons.

<p>(A) Detection of <i>Kv3</i>.<i>1</i>, <i>Kv3</i>.<i>2</i>, and <i>Hcn2</i> subunit genes by RT-qPCR analysis after harvesting the cytoplasm from single LH^PV neurons. Representative amplification plot displayed. Note that cells were <i>Pvalb</i>⁺/<i>Vglut2</i>⁺/<i>Vgat</i>⁻. (B) Relative abundance of <i>Kv3</i>.<i>1</i>, <i>Kv3</i>.<i>2</i>, and <i>Hcn2</i> in single LH^PV neurons. Box plots show mean (×), median, quartiles (boxes), and s.e.m. (whiskers). Cycle threshold (Ct), relative abundance values, and sample sizes are explained in Methods. (C) Representative firing pattern of a fast-spiking LH^PV neuron that displays spike frequency accommodation and amplitude attenuation during large depolarizing current injections (500 pA, 500 ms pulses). Note decreases in firing frequency and amplitude during the last 100 ms of the pulse. Dotted line denotes resting membrane potential (V_rmp = –63 mV). (D) Firing rate of LH^PV neurons in response to current injection (<i>I–f</i> curves) during 500 ms pulses. The red/gray dots show the average firing rate of the LH^PV neurons and the standard deviation is indicated by the black vertical bar (<i>n</i> = 34).</p

Axonal projections of LH^PV neurons.

<p>(A) Schematic and representative image depicting a bilateral injection of the Cre recombinase-dependent viral vector for anterograde tracing (rAAV2/9-hEf1α-DIO-synaptophysin-mCherry) into the lateral hypothalamus (LH) of a <i>Pvalb</i>^{<i>IREScre</i>} mouse. Scale bar 500 μm. Representative images of projections to (B) the lateral habenula (LHb), (C) the submedius thalamic nucleus (Sub), (D) the parafascicular thalamic nucleus (PF) surrounding the fasciculus retroflexus (fr), (E) the posterior hypothalamus (PH), (F) the retromamillary nucleus (RMM), (G) the periaqueductal gray (PAG), and (H) the reticulotegmental nucleus of the pons (RtTg). (B-D-E-F) Scale bars (low magnification), 200 μm; Scale bars (high magnification), 25 μm (C-G-H) Scale bars (low magnification), 100 μm; Scale bars (high magnification), 25 μm. (<i>n</i> = 3 mice). Schematic images modified from Franklin KBJ & Paxinos G (2013) [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0198991#pone.0198991.ref027" target="_blank">27</a>].</p