The Effect of Vitamin A on Cellular Differentiation and Mucous Glycoprotein Synthesis in Long-Term Rat Tracheal Organ Cultures

Rat tracheal explants maintained as organ cultures exhibited a normal mucociliary epithelium for at least 46 days in the presence of retinyl acetate. In the absence of vitamin A the explant epithelium became quiescent or underwent a metaplastic change to a keratinizing squamous epithelium. This process was accelerated if explants were derived from vitamin A-deficient animals. Autoradiographic examination showed that [³H]glucosamine label accumulated in various cell types in the explant, but especially in the epithelium. It was found that the explants secreted mucous glycoproteins into the medium and that the production and biochemical characteristics of a specific mucin fraction were dependent upon the vitamin A status of the explant.     

Flag Leaf Anatomy of Triticum and Aegilops Species in Relation to Photosynthetic Rate

Quantitative anatomical and other measurements were made onfully expanded flag leaves of a series of diploid, tetraploidand hexaploid Triticum and Aegilops species, and photosyntheticrates per unit leaf area were measured at light saturation (P_max). Diploids had the highest P_max, hexaploids the lowest with tetraploidsbeing intermediate. The anatomical features of tetraploids andhexaploids were generally similar, but different from the diploids.The diploids had thinner leaves with less dry matter and chlorophyllper unit area. The surface area of the mesophyll cells per unitvolume of mesophyll tissue was similar for all ploidy levels,as was the ratio mesophyil cell surface area per unit leaf area.It is argued that while these anatomical features are unlikelyto account for the observed variation in Pmax, it is possiblethat other structural factors with which they are correlatedmay causally influence P_max. One such feature is the averagediffusion path length from the plasmalemma at the cell surfaceto the sites of carboxylation. Anatomy, photosynthesis, mesophyll, cell size, Triticum, Aegilops, polyploidy     

Microsatellite markers isolated from polyploid wood‐sorrel Oxalis alpina (Oxalidaceae)

Twelve polymorphic microsatellite loci were isolated from polyploid alpine wood‐sorrel, Oxalis alpina (Oxalidaceae), and optimized for future studies of its breeding system. The loci were screened for variability among 72 individuals from Pinos Altos, New Mexico. The primers amplified loci with allele number ranging from two to 17 per locus and with estimates of Nei's genetic diversity varying from 0.10 to 0.99. These primers provide an opportunity to use polymorphic DNA markers to study the causes of breeding system variability in this species.     

Twelve polymorphic microsatellite loci from the Asian citrus psyllid,Diaphorina citri Kuwayama,the vector for citrus greening disease,huanglongbing

Twelve polymorphic microsatellite markers were developed from microsatellite‐enriched DNA libraries and mined from an expressed sequence tags library of Diaphorina citri, the vector of the citrus greening disease (huanglongbing). Analysis of 288 individuals from Florida, Texas, and Brazil showed that allelic diversity ranged from three to eight alleles per locus and observed and expected heterozygosities ranged from 0.014 to 0.569 and from 0.052 to 0.653, respectively. These variable microsatellite loci can provide means for assessing overall genetic variation and migration patterns for this agriculturally important pest species. This information can be used to aid in developing successful management strategies.     

Long‐distance signals influence assessment of close range mating displays in the field cricket,Gryllus integer

Male sexual displays often include components detected across long distances, and those perceived only at close range. Understanding what information females gain from each component of a complex display and how they use these signals to make decisions are questions of major interest in sexual selection research. We evaluated content‐based hypotheses (‘redundant signals’ and ‘multiple messages’) for the courtship displays of field crickets (Gryllus integer) by measuring female responses to males' long‐distance calling song (calls) and close‐range chemical cues. Females' responses to a male's calls and chemical cues were uncorrelated, supporting the ‘multiple messages’ hypothesis. We also tested the ‘inter‐signal interaction’ hypothesis by investigating how long‐distance calls influence evaluation of close‐range courtship. The relationship between long‐ and close‐range signals was complex and conditional: females accepted close‐range courtship more quickly after exposure to attractive calling song than they did after exposure to either unattractive calling song or silence, and unattractive calls were no more or less effective than silence. This inter‐signal interaction could affect our understanding of mate choice in species with multiple mating signals because it implies that females may save time and energy by not assessing the close‐range signals of attractive long‐distance signalers. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 856–865.     

Connectivity,small islands and large distances: the Cellana strigilis limpet complex in the Southern Ocean

The Southern Ocean contains some of the most isolated islands on Earth, and fundamental questions remain regarding their colonization and the connectivity of their coastal biotas. Here, we conduct a genetic investigation into the Cellana strigilis (limpet) complex that was originally classified based on morphological characters into six subspecies, five of which are endemic to the New Zealand (NZ) subantarctic and Chatham islands (44–52°S). Previous genetic analyses of C. strigilis from six of the seven island groups revealed two lineages with little or no within‐lineage variation. We analysed C. strigilis samples from all seven island groups using two mitochondrial (COI and 16S), one nuclear (ATPase β) and 58 loci from four randomly amplified polymorphic DNA markers (RAPDs) and confirmed the existence of two distinct lineages. The pronounced genetic structuring within each lineage and the presence of private haplotypes in individual islands are the result of little genetic connectivity and therefore very high self‐recruitment. This study supports the significance of the subantarctic islands as refugia during the last glacial maximum and adds to the knowledge of contemporary population connectivity among coastal populations of remote islands in large oceans and the distance barrier to gene flow that exists in the sea (despite its continuous medium) for most taxa.     

Characterization of polymorphic microsatellite loci for the polychaete tubeworm Hobsonia florida

Eight dinucleotide microsatellite loci were isolated and characterized from Hobsonia florida, a tube‐dwelling ampharetid polychaete. The identified loci were highly polymorphic, with allelic diversity ranging from six to 11 alleles. Levels of expected heterozygosity were 0.52 or greater in all cases, averaging 0.78 across the complete set of loci. Cross‐species amplification was successful in three of the eight loci for one or both of the other species (Melinna cristata and Ampharete acutifrons) tested. Although these novel loci were designed for immediate utility in H. florida population‐level research, these results indicate they may prove useful in studies of other related taxa.