Biology subjects

Dutta, R.

Publications and source records attributed to Dutta, R..

4 recordsLinked to original sources

bioRxiv2018

The role of sexual conflict, sexual selection and ancestry in the evolution of chemical sexual signals

The ability of interlocus sexual conflict to facilitate reproductive isolation is widely anticipated. However, very few experimental evolutionary studies have convincingly demonstrated the evolution of reproductive isolation due to sexual conflict. Recently a study on replicate populations of Drosophila melanogaster under differential sexual conflict found that divergent mate preference evolved among replicate populations under high sexual conflict regime. The precopulatory isolating mechanism underlying such divergent mate preference could be sexual signals such as cuticular hydrocarbons since they evolve rapidly and are involved in D. melanogaster mate recognition. Using D. melanogaster replicates used in the previous study, we investigate whether cuticular hydrocarbon divergence bears signatures of sexually antagonistic coevolution that led to reproductive isolation among replicates of high sexual conflict regime. We found that D. melanogaster cuticular hydrocarbon profiles are sexually dimorphic. Although replicate populations under high sexual conflict displayed assortative mating, we found no significant differences in the cuticular hydrocarbon profile between the high and low sexual conflict regimes. Instead we find cuticular hydrocarbon divergence patterns to be suggestive of the Buridans Ass regime which is one of the six possible mechanisms to resolve sexual conflict. Sexual selection that co-vary between populations under high and low sexual conflict regimes may also have contributed to the evolution of cuticular hydrocarbons. This study indicates that population differentiation as a result of cuticular hydrocarbon divergence cannot be credited to sexual conflict despite high sexual conflict regime evolving divergent cuticular hydrocarbon profiles.

evolutionary biology↗

bioRxiv2018

Gold Nanoprisms as Optical Coherence Tomography Contrast Agents in the Second Near Infrared Window for Enhanced Angiography in Live Animals

Optical coherence tomography angiography (OCTA) is an important tool for investigating vascular networks and microcirculation in living tissue. Traditional OCTA detects blood vessels via intravascular dynamic scattering signals derived from the movements of red blood cells (RBCs). However, the low hematocrit and long latency between RBCs in capillaries makes these OCTA signals discontinuous, leading to incomplete mapping of the vascular networks. OCTA imaging of microvascular circulation is particularly challenging in tumors due to the abnormally slow blood flow in angiogenic tumor vessels and strong attenuation of light by tumor tissue. Here we demonstrate in vivo that gold nanoprisms (GNPRs) can be used as OCT contrast agents working in the second near infrared window, significantly enhancing the dynamic scattering signals in microvessels and improving the sensitivity of OCTA in skin tissue and melanoma tumors in live mice. This is the first demonstration that nanoparticle-based OCT contrast agent work in vivo in the second near infrared window, which allows deeper imaging depth by OCT. With GNPRs as contrast agents, the post-injection OCT angiograms showed 41% and 59% more microvasculature than pre-injection angiograms in healthy mouse skin and melanoma tumors, respectively. By enabling better characterization of microvascular circulation in vivo, GNPR-enhanced OCTA could lead to better understanding of vascular functions during pathological conditions, more accurate measurements of therapeutic response, and improved patient prognoses.

bioengineering↗

bioRxiv2018

High-resolution wide-field human brain tumor margin detection and in vivo murine neuroimaging

Current in vivo neuroimaging techniques provide limited field of view or spatial resolution and often require exogenous contrast. These limitations prohibit detailed structural imaging across wide fields of view and hinder intraoperative tumor margin detection. Here we present a novel neuroimaging technique, speckle-modulating optical coherence tomography (SM-OCT), which allows us to image the brains of live mice and ex vivo human samples with unprecedented resolution and wide field of view using only endogenous contrast. The increased effective resolution provided by speckle elimination reveals white matter fascicles and cortical layer architecture in the brains of live mice. To our knowledge, the data reported herein represents the highest resolution imaging of murine white matter structure achieved in vivo across a wide field of view of several millimeters. When applied to an orthotopic murine glioblastoma xenograft model, SM-OCT readily identifies brain tumor margins with near single-cell resolution. SM-OCT of ex vivo human temporal lobe tissue reveals fine structures including cortical layers and myelinated axons. Finally, when applied to an ex vivo sample of a low-grade glioma resection margin, SM-OCT is able to resolve the brain tumor margin. Based on these findings, SM-OCT represents a novel approach for intraoperative tumor margin detection and in vivo neuroimaging.

bioengineering↗

bioRxiv2017

Wide-field dynamic monitoring of immune cell trafficking in murine models of glioblastoma

Leukocyte populations, especially tumor-associated macrophages (TAMs), are capable of mediating both anti- and pro-tumor processes and play significant roles in the tumor microenvironment. Moreover, TAMs have been shown to exert substantial influence on the efficacy of various cancer immunotherapy treatment strategies. Laboratory investigation into the behavior of TAMs has been limited by a lack of methods capable of resolving the in vivo distribution and dynamics of this cell population across wide fields of view. Recent studies have employed magnetic resonance imaging and intravital microscopy in conjunction with nanoparticle labeling methods to detect TAMs and observe their responses to therapeutic agents. Here we describe a novel method to enable high-resolution, wide-field, longitudinal imaging of leukocytes based on contrast-enhanced Speckle-Modulating Optical Coherence Tomography (SM-OCT), which substantially reduces imaging noise. We were able to specifically label TAMs and activated microglia in vivo with large gold nanorod contrast agents (LGNRs) in an orthotopic murine glioblastoma model. After labeling, we demonstrated near real-time tracking of leukocyte migration and distribution within the tumors. The intrinsic resolution, imaging depth, and sensitivity of this method may facilitate detailed studies of the fundamental behaviors of TAMs in vivo, including their intratumoral distribution heterogeneity and the roles they play in modulating cancer proliferation. In future studies, the method described herein may also provide the necessary means to characterize TAM responses to immunotherapeutic regimens in a range of solid tumors.

bioengineering↗