In memoriam: Richard G. Harrison - his life and legacy.

Richard G. Harrison passed away unexpectedly on April 12th, 2016. In this memoriam we pay tribute to the life and legacy of an extraordinary scientist, mentor, friend, husband, and father.

Genetics and the origin of species: the continuing synthesis: a symposium in honor of Richard G. Harrison.

This is a special issue of that has its origins in a symposium held in honor of Richard G. Harrison at Ithaca, New York on July 22–23. Former students of Rick Harrison organized the symposium and most of the speakers were former students, as well.

Label-free DNA methylation analysis using opto-fluidic ring resonators.

The opto-fluidic ring resonator (OFRR) is a sensitive label-free optical biosensor that is uniquely well suited for photonic and fluidic integration. For the first time we have explored the utility of this novel instrument for the analysis of methylation in oligonucleotides using the MBD-2 (methyl binding) protein as the capture molecule. This application has strong relevance to cancer research and future clinical tools through the study of methylation patterns in important gene promoters.

Demonstration of the coupling of optofluidic ring resonator lasers with liquid waveguides.

Optofluidic lasers are of particular interest for lab-on-a-chip-type devices, with broad spectral tunability, convenient microfluidic integration, and a small footprint. Optofluidic ring resonator (OFRR) lasers are advantageous in terms of size but typically generate nondirectional emission that is of minimal practical use. We introduce two unique geometries for soft-lithography-based OFRR lasers--side-coupled rings and spiral rings--both of which can be produced in polydimethyl siloxane substrates with contact molding.

Comparative proteomics uncovers the signature of natural selection acting on the ejaculate proteomes of two cricket species isolated by postmating, prezygotic phenotypes.

Two of the most well-supported patterns to have emerged over the past two decades of research in evolutionary biology are the occurrence of divergent natural selection acting on many male and female reproductive tract proteins and the importance of postmating, prezygotic phenotypes in reproductively isolating closely related species. Although these patterns appear to be common across a wide variety of taxa, the link between them remains poorly documented. Here, we utilize comparative proteomic techniques to determine whether or not there is evidence for natural selection acting on the ejaculate proteomes of two cricket species (Allonemobius fasciatus and A.

Fabry-Pérot cavity sensors for multipoint on-column micro gas chromatography detection.

We developed and characterized a Fabry-Pérot (FP) sensor module based micro gas chromatography (microGC) detector for multipoint on-column detection. The FP sensor was fabricated by depositing a thin layer of metal and a layer of gas-sensitive polymer consecutively on the endface of an optical fiber, which formed the FP cavity. Light partially reflected from the metal layer and the polymer-air interface generated an interference spectrum, which shifted as the polymer layer absorbed the gas analyte.

Antagonism of macrophage migration inhibitory factor decreases cyclophosphamide cystitis in mice.

Aims: Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine found pre-formed in the urothelium. During inflammation, MIF is released into the bladder lumen and bladder MIF mRNA is upregulated. Since MIF also has tautomerase activity and blocking tautomerase activity also blocks MIF's biological activity, we hypothesized that blocking MIF's tautomerase activity would prevent bladder inflammation.

Rapid tandem-column micro-gas chromatography based on optofluidic ring resonators with multi-point on-column detection.

We demonstrated a novel tandem-column micro-gas chromatography (microGC) based on optofluidic ring resonator (OFRR). The OFRR is a thin-walled fused silica capillary whose interior surface is coated with a polymeric stationary phase. The circular cross section of the OFRR forms the micro-ring resonator and supports whispering gallery modes (WGMs).

Label-free analysis of DNA methylation using optofluidic ring resonators.

We demonstrate the utility of the opto-fluidic ring resonator (OFRR) sensor for analyzing methylated oligonucleotides. Cytosine methylation, a regular epigenetic function in cellular growth and metabolism, may have ties to abnormal suppression of key genes involved with cellular proliferation. Such behavior is suspected to be strongly related to the occurrence of several types of cancers.

The genetics of reproductive isolation: a retrospective and prospective look with comments on ground crickets.

An intriguing aspect of the current renaissance in investigations of the genetics of reproductive isolation is that it has been dominated by studies that resemble work done in the 1930s, 1940s, and 1950s. The dominant model organism (Drosophila), research approaches, and traits of interest (sterility and inviability of hybrids) all harken back to this earlier era. Herein, we explore the factors that led to a rebirth of interest in the genetics of reproductive isolation and to the adoption of the approaches of an earlier generation of biologists.

PDMS embedded opto-fluidic microring resonator lasers.

Opto-fluidic ring resonator (OFRR) dye lasers are embedded in low index polydimethylsiloxane (PDMS) to achieve enhanced portability, mechanical stability, and potential integration with conventional soft lithography based microfluidics for development of micro total analysis systems. The OFRR retains high Q-factors (> 10(6)) and exhibits low lasing threshold (<1 microJ/mm(2)). Fiber prisms and tapered optical fibers are used to directionally couple out the laser emission.

Genetic architecture of conspecific sperm precedence in Allonemobius fasciatus and A. socius.

The evolution of barriers to gene exchange is centrally important to speciation. We used the crickets Allonemobius fasciatus and A. socius to investigate the genetic architecture of conspecific sperm precedence (CSP), a postinsemination prezygotic reproductive barrier.

Identification and comparative analysis of accessory gland proteins in Orthoptera.

Accessory reproductive gland proteins (Acps) in Drosophila evolve quickly and appear to play an important role in ensuring the fertilization success of males. Moreover, Acps are thought to be involved in establishing barriers to fertilization between closely related species. While accessory glands are known to occur in the males of many insect groups, the proteins that are passed on to females by males during mating have not been well characterized outside of Drosophila.

Clustering of contact zones, hybrid zones, and phylogeographic breaks in North America.

A recent test for the existence of suture zones in North America, based on hybrid zones studied since 1970, found support for only two of the 13 suture zones identified by Remington in 1968 (Swenson and Howard 2004). One limitation of that recent study was the relatively small number of hybrid zones available for mapping. In this study, we search for evidence of clustering of contact zones between closely related taxa using data not only from hybrid zones but from species range maps of trees, birds, and mammals and from the position of phylogeographic breaks within species.

Do suture zones exist?

Remington (1968) argued that 13 suture zones exist in North America. Remington defined a suture zone as, "a band of geographic overlap between major biotic assemblages, including some pairs of species or semispecies which hybridize in the zone" (p. 322).

REINFORCING SELECTION IS EFFECTIVE UNDER A RELATIVELY BROAD SET OF CONDITIONS IN A MOSAIC HYBRID ZONE.

Many hybrid zones have a mosaic structure, yet we know of no theoretical work that examines the impact of mosaicism on the outcome of evolution. We developed a computer simulation model designed to test whether the outcome of reinforcing selection differs in a mosaic and a clinal hybrid zone. Our model was a one-dimensional stepping-stone model.

VARIATION IN GENETIC ARCHITECTURE OF CALLING SONG AMONG POPULATIONS OF ALLONEMOBIUS SOCIUS, A. FASCIATUS, AND A HYBRID POPULATION: DRIFT OR SELECTION?

Predictions using quantitative genetic models generally assume that the variance-covariance matrices remain constant over time. This assumption is based on the supposition that selection is generally weak and hence variation lost through selection can be replaced by new mutations. Whether this is generally true can only be ascertained from empirical studies.

GENETIC VARIATION IN CRICKET CALLING SONG ACROSS A HYBRID ZONE BETWEEN TWO SIBLING SPECIES.

The sibling ground crickets Allonemobius fasciatus and A. socius meet along a mosaic hybrid zone at ≈ 40°N latitude in eastern North America. In this paper we report the findings of a genetic analysis of calling-song variation within and among six cricket populations sampled along a transect through the hybrid zone in southern New Jersey.

CONSPECIFIC SPERM PRECEDENCE IS AN EFFECTIVE BARRIER TO HYBRIDIZATION BETWEEN CLOSELY RELATED SPECIES.

Conspecific sperm precedence is widespread in animals, appears to evolve rapidly, and is thought to have the potential to prevent hybridization between closely related species. However, to date no study has tested the isolating potential of such a barrier in mixed populations of two taxa under conditions in which other potential barriers to gene flow are controlled for or are prevented from operating. We tested the isolating potential of conspecific sperm precedence in the ground crickets Allonemobius fasciatus and A.

HOW DISCRETE ARE OAK SPECIES? INSIGHTS FROM A HYBRID ZONE BETWEEN QUERCUS GRISEA AND QUERCUS GAMBELII.

The white oaks Quercus gambelii and Q. grisea overlap in distribution in New Mexico and Arizona. Within the region of overlap, there are numerous instances of contact between the two taxa.

LACK OF CALLING SONG DISPLACEMENT BETWEEN TWO CLOSELY RELATED GROUND CRICKETS.

Thorough examinations of purported cases of reproductive character displacement are critical for reaching an understanding of the role of reinforcement in the evolution of reproductive barriers between closely related species. In this paper, we report the results of an extensive investigation of male calling song variation in the ground crickets, Allonemobius fasciatus and A. socius.

A POSTINSEMINATION BARRIER TO FERTILIZATION ISOLATES TWO CLOSELY RELATED GROUND CRICKETS.

Postinsemination barriers to fertilization generally have been ignored by biologists interested in the origin and nature of reproductive isolation among closely related terrestrial animals. Yet evidence presented in this paper indicates that such a barrier bears primary responsibility for the reproductive isolation between the ground crickets Allonemobius fasciatus and Allonemobius socius. Postinsemination barriers to fertilization may isolate many other terrestrial animals as well, but the design of most laboratory hybridization experiments precludes the detection of these barriers.

SURVIVAL OF HYBRIDS IN A MOSAIC HYBRID ZONE.

The ground crickets Allonemobius fasciatus and A. socius meet in a mosaic hybrid zone that stretches from New Jersey at least as far west as Illinois. Within mixed populations from the contact zone, "pure" species individuals predominate.

CALLING SONG DISPLACEMENT IN A ZONE OF OVERLAP AND HYBRIDIZATION.

The ground crickets Allonemobius fasciatus and A. socius meet in a mosaic zone of overlap and hybridization stretching from the East Coast to at least Illinois. To test whether male calling song differences were enhanced in sympatry, we analyzed the songs of crickets from inside and outside the zone of overlap along two transects.

TOPOGRAPHIC DIVERSITY, ZONE WIDTH, AND THE STRENGTH OF REPRODUCTIVE ISOLATION IN A ZONE OF OVERLAP AND HYBRIDIZATION.

Two closely related species of ground crickets, Allonemobius fasciatus and A. socius, overlap and hybridize in a contact zone in the eastern United States. In earlier work, Howard (1986) described geographic variation in the width of the zone and in the strength of reproductive isolation between the two ground crickets.