Publications by authors named "Brittany J Belin"

The symbioses between leguminous plants and nitrogen-fixing bacteria known as rhizobia are well known for promoting plant growth and sustainably increasing soil nitrogen. Recent evidence indicates that hopanoids, a family of steroid-like lipids, promote symbioses with tropical legumes. To characterize hopanoids in symbiosis with soybean, we validated a recently published cumate-inducible hopanoid mutant of diazoefficiens USDA110, Pcu-::∆.

View Article and Find Full Text PDF

Unlabelled: The symbioses between leguminous plants and nitrogen-fixing bacteria known as rhizobia are well known for promoting plant growth and sustainably increasing soil nitrogen. Recent evidence indicates that hopanoids, a family of steroid-like lipids, promote symbioses with tropical legumes. To characterize hopanoids in symbiosis with soybean, the most economically significant host, we validated a recently published cumate-inducible hopanoid mutant of USDA110, Pcu- ::Δ .

View Article and Find Full Text PDF

The formation of lateral microdomains is emerging as a central organizing principle in bacterial membranes. These microdomains are targets of antibiotic development and have the potential to enhance natural product synthesis, but the rules governing their assembly are unclear. Previous studies have suggested that microdomain formation is promoted by lipid phase separation, particularly by cardiolipin (CL) and isoprenoid lipids, and there is strong evidence that CL biosynthesis is required for recruitment of membrane proteins to cell poles and division sites.

View Article and Find Full Text PDF

Bacteria are a globally sustainable source of fixed nitrogen, which is essential for life and crucial for modern agriculture. Many nitrogen-fixing bacteria are agriculturally important, including bacteria known as rhizobia that participate in growth-promoting symbioses with legume plants throughout the world. To be effective symbionts, rhizobia must overcome multiple environmental challenges: from surviving in the soil, to transitioning to the plant environment, to maintaining high metabolic activity within root nodules.

View Article and Find Full Text PDF

Hopanoids are steroid-like bacterial lipids that enhance membrane rigidity and promote bacterial growth under diverse stresses. Hopanoid biosynthesis genes are conserved in nitrogen-fixing plant symbionts, and we previously found that the extended (C) class of hopanoids in are required for efficient symbiotic nitrogen fixation in the tropical legume host . Here, we demonstrate that the nitrogen-fixation defect conferred by extended hopanoid loss can be fully explained by a reduction in root nodule sizes rather than per-bacteroid nitrogen-fixation levels.

View Article and Find Full Text PDF

Lipid research represents a frontier for microbiology, as showcased by hopanoid lipids. Hopanoids, which resemble sterols and are found in the membranes of diverse bacteria, have left an extensive molecular fossil record. They were first discovered by petroleum geologists.

View Article and Find Full Text PDF

Fluorescent derivatives of actin and actin-binding domains are powerful tools for studying actin filament architecture and dynamics in live cells. Growing evidence, however, indicates that these probes are biased, and their cellular distribution does not accurately reflect that of the cytoskeleton. To understand the strengths and weaknesses of commonly used live-cell probes--fluorescent protein fusions of actin, Lifeact, F-tractin, and actin-binding domains from utrophin--we compared their distributions in cells derived from various model organisms.

View Article and Find Full Text PDF

Actin filaments assemble inside the nucleus in response to multiple cellular perturbations, including heat shock, protein misfolding, integrin engagement, and serum stimulation. We find that DNA damage also generates nuclear actin filaments-detectable by phalloidin and live-cell actin probes-with three characteristic morphologies: (i) long, nucleoplasmic filaments; (ii) short, nucleolus-associated filaments; and (iii) dense, nucleoplasmic clusters. This DNA damage-induced nuclear actin assembly requires two biologically and physically linked nucleation factors: Formin-2 and Spire-1/Spire-2.

View Article and Find Full Text PDF

In the cytoplasm, actin filaments form crosslinked networks that enable eukaryotic cells to transport cargo, change shape, and move. Actin is also present in the nucleus but, in this compartment, its functions are more cryptic and controversial. If we distill the substantial literature on nuclear actin down to its essentials, we find four, recurring, and more-or-less independent, claims: (1) crosslinked networks of conventional actin filaments span the nucleus and help maintain its structure and organize its contents; (2) assembly or contraction of filaments regulates specific nuclear events; (3) actin monomers moonlight as subunits of chromatin remodeling complexes, independent of their ability to form filaments; and (4) modified actin monomers or oligomers, structurally distinct from canonical, cytoskeletal filaments, mediate nuclear events by unknown mechanisms.

View Article and Find Full Text PDF

In addition to its long-studied presence in the cytoplasm, actin is also found in the nuclei of eukaryotic cells. The function and form (monomer, filament, or noncanonical oligomer) of nuclear actin are hotly debated, and its localization and dynamics are largely unknown. To determine the distribution of nuclear actin in live somatic cells and evaluate its potential functions, we constructed and validated fluorescent nuclear actin probes.

View Article and Find Full Text PDF

A PHP Error was encountered

Severity: Warning

Message: fopen(/var/lib/php/sessions/ci_sessionhvgu4l9ov7ijeuvfdak604d328eihq96): Failed to open stream: No space left on device

Filename: drivers/Session_files_driver.php

Line Number: 177

Backtrace:

File: /var/www/html/index.php
Line: 316
Function: require_once

A PHP Error was encountered

Severity: Warning

Message: session_start(): Failed to read session data: user (path: /var/lib/php/sessions)

Filename: Session/Session.php

Line Number: 137

Backtrace:

File: /var/www/html/index.php
Line: 316
Function: require_once