Spatial Patterns in Antibiotic Resistance among Stream Bacteria: Effects of Industrial Pollution

The spatial distribution of antibiotic resistance to streptomycin and kanamycin was examined in natural bacterial communities of two streams. The proportion of resistant bacteria was substantially higher (P < 0.05) in the midreaches of an industrially perturbed stream, but no such pattern was apparent in an undisturbed reference stream. The highest relative frequency of resistance was found at the confluence of a tributary draining a nuclear reactor and industrial complex. Antibiotic resistance increased with distance upstream from the confluence and was positively correlated (r² = 0.54, P = 0.023) with mercury concentrations in the sediments. When the data for two years were compared, this pattern was stable for streptomycin resistance (paired t test, P < 0.05) but not for kanamycin resistance (P > 0.05). Our results imply that heavy metal pollution may contribute to increased antibiotic resistance through indirect selection.     

Genetic diversity vs geographic distribution of five congeneric caddisflies

We compared the genetic structure and diversity offive Cheumatopsyche (Trichoptera:Hydropsychidae) species from Upper Three Runs Creek inSouth Carolina to analyze the relationship betweengenetic variability and potential gene flow (i.e.,geographic distribution) in a group of loticmacroinvertebrates. Among these species is an endemicto the stream (Cheumatopsyche richardsoni), asoutheastern U.S.A. endemic (C. edista), andthree widely distributed species (C. pasella,C. pettiti, and C. pinaca). Usingcellulose acetate plates, we reliably scored 19presumptive allozyme loci for each species. C. richardsoni and C. pettiti were the leastgenetically variable taxa, C. pasella and C. pinaca the most, and C. edista fell inbetween. Therefore, unless this C. pettitipopulation is not representative of the species ingeneral, the genetic diversity of C. richardsoniand C. edista fall within the range exhibited byother congeners. In turn, each species’ geneticdiversity is evidently not correlated to its relativegeographic distribution. Four species (all but C. pettiti) had moderate to high proportions ofpolymorphic loci in Hardy-Weinberg disequilibria, thecause of which is likely one of three factors: (1) eachspecies experiences disruptive selection, (2) weinadvertently sampled adults from more than onegenetically distinct stream population, or (3) eachspecies is divided into partially reproductivelyisolated subpopulations within the stream. This revised version was published online in July 2006 with corrections to the Cover Date.     

Identification of a Novel Recycling Sequence in the C-tail of FPR2/ALX Receptor: ASSOCIATION WITH CELL PROTECTION FROM APOPTOSIS*

Formyl-peptide receptor type 2 (FPR2; also called ALX because it is the receptor for lipoxin A₄) sustains a variety of biological responses relevant to the development and control of inflammation, yet the cellular regulation of this G-protein-coupled receptor remains unexplored. Here we report that, in response to peptide agonist activation, FPR2/ALX undergoes β-arrestin-mediated endocytosis followed by rapid recycling to the plasma membrane. We identify a transplantable recycling sequence that is both necessary and sufficient for efficient receptor recycling. Furthermore, removal of this C-terminal recycling sequence alters the endocytic fate of FPR2/ALX and evokes pro-apoptotic effects in response to agonist activation. This study demonstrates the importance of endocytic recycling in the anti-apoptotic properties of FPR2/ALX and identifies the molecular determinant required for modulation of this process fundamental for the control of inflammation.     

Air movement and heat loss from sheep. II. Thermal insulation of fleece in wind

Penetration of an animal's coat by wind reduces its thermal insulation and increases heat loss to the environment. From studies of the sensible heat loss from a life-sized model sheep covered with fleece, the average fleece resistance -rf(s cm-1) was related to windspeed u (m s-1) by 1/-rf(u) = 1/-rf(0)+cu, where c is a dimensionless constant. As c is expected to be inversely proportional to coat depth l, the more general relation -k(u) = -k(0)+c'u was evaluated, where -k = l/-rf is the thermal diffusivity (cm2 s-1) of the fleece and c' = cl is another constant (cm). The orientation of the model to the wind had little effect on the bulk resistance of the fleece, but the resistance on the windward side was substantially lower than on the leeward side.     

Epithalamus of the nine-banded armadillo, Dasypus novemcinctus

The epithalamus of embryonic, neonatal and adult nine-banded armadillo (Dasypus novemcinctus) was examined for evidence of pineal-like tissue. The evagination of the diencephalic roof (the anlage of the epiphysis) was not found in any embryonic specimens. In the adult brain, the epithalamus is dominated by the sub-commissural organ (SCO) which is surrounded entirely by the posterior commissure. At the most caudal aspect of the SCO, previous investigators have observed pineal-like tissue. Using pineal-specific staining techniques however, we found no evidence of this tissue. Because the armadillo produces melatonin in a rhythmic manner, exhibits exacting circadian rhythms, and shows altered rhythms when exposed to exogenous melatonin, we believe other organs, perhaps the retina or Harderian gland, must be involved in maintaining the coordinated melatonin titer.     

Loss of CDKN2A expression is a frequent event in primary invasive melanoma and correlates with sensitivity to the CDK4/6 inhibitor PD0332991 in melanoma cell lines

We have investigated the potential for the p16‐cyclin D‐CDK4/6‐retinoblastoma protein pathway to be exploited as a therapeutic target in melanoma. In a cohort of 143 patients with primary invasive melanoma, we used fluorescence in situ hybridization to detect gene copy number variations (CNVs) in CDK4, CCND1, and CDKN2A and immunohistochemistry to determine protein expression. CNVs were common in melanoma, with gain of CDK4 or CCND1 in 37 and 18% of cases, respectively, and hemizygous or homozygous loss of CDKN2A in 56%. Three‐quarters of all patients demonstrated a CNV in at least one of the three genes. The combination of CCND1 gain with either a gain of CDK4 and/or loss of CDKN2A was associated with poorer melanoma‐specific survival. In 47 melanoma cell lines homozygous loss, methylation or mutation of CDKN2A gene or loss of protein (p16^INK4A) predicted sensitivity to the CDK4/6 inhibitor PD0332991, while RB1 loss predicted resistance.     

Removing the rubbish: frogs eliminate foreign objects from the body cavity through the bladder

During the course of a telemetry study on three species of Australian frogs (Litoria caerulea, Litoria dahlii and Cyclorana australis), we found that many of the surgically implanted transmitters had migrated into the bladder. We subsequently implanted small beads into L. caerulea and they were expelled from the body in 10-23 days. Beads implanted into cane toads (Rhinella marina) to document the process were either expelled or were enveloped into the bladder. This appears to be a unique pathway for expulsion of foreign objects from the body, and suggests that caution should be employed in telemetry studies when interpreting the separation of some animals from their transmitters as a mortality event.     

Arginine functionalization of hydrogels for heparin binding—a supramolecular approach to developing a pro‐angiogenic biomaterial

Our aim was to synthesize a biomaterial that stimulates angiogenesis for tissue engineering applications by exploiting the ability of heparin to bind and release vascular endothelial growth factor (VEGF). The approach adopted involved modification of a hydrogel with positively charged peptides (oligolysine or oligoarginine) to achieve heparin binding. Precursor hydrogels were produced from copolymerization of N‐vinyl pyrolidone, diethylene glycol bis allyl carbonate and acrylic acid (PNDA) and functionalized after activation of the carboxylic acid groups with trilysine or triarginine peptides (PNDKKK and PNDRRR). Both hydrogels were shown to bind and release bioactive VEGF165 with arginine‐modified hydrogel outperforming the lysine‐modified hydrogel. Cytocompatibility of the hydrogels was confirmed in vitro with primary human dermal fibroblasts and human dermal microvascular endothelial cells (HUDMECs). Proliferation of HUDMECs was stimulated by triarginine‐functionalized hydrogels, and to a lesser extent by lysine functionalized hydrogels once loaded with heparin and VEGF. The data suggests that heparin‐binding hydrogels provide a promising approach to a pro‐angiogenic biomaterial. Biotechnol. Bioeng. 2013; 110: 296–317. © 2012 Wiley Periodicals, Inc.