Morphological and histochemical features of the duodenal glands in six marsupial species

The duodenal glands of four marsupial species, the kangaroo, native cat, marsupial mouse, and bandicoot, form a narrow lobular collar immediately distal to the gastrointestinal junction. In two species, the koala and wombat, the duodenal glands are diffuse and scattered along the intestinal tract distal to the gastrointestinal junction for considerable distances. The glands of all species examined empty independently into the intestinal lumen. Histochemical studies indicate that the latter two species, the koala and wombat, elaborate an acid mucin whereas the former species produce a neutral mucosubstance. Ultrastructural examination shows that generally the duodenal glands are comprised of large pyramidal cells that show a definite polarity, with basally-placed nuclei and apically-situated secretory granules. Species differences, with regard both to the morphology and nature of the secretory granules and to the proportions of cell organelles, exist. The diversity of diet between species is discussed.     

Morphological analysis of some cryptic species in the Acanthocyclops vernalis species complex from North America

Patterns of morphological variation and reproductive isolation were examined for several North American populations of copepods in the Acanthocyclops vernalis Fischer A., 1853 (Copepoda, Cyclopinae) species complex. The copepods were collected from six sites in Wisconsin, U.S.A. Morphological analysis of 120 adult females revealed that a character used previously to distinguish species in this group was unreliable because of phenotypic plasticity. Most of the morphological variance was due to environment (Laboratory vs. field) and to field site. Relatively little of the variation was due to measurement error or asymmetry. Multivariate ordination analysis produced poorly-defined clusters of individuals, suggesting that different biological species are difficult or impossible to distinguish using a set of easily-measurable morphological characters. In our study, morphological similarity was independent of geographic distance among sites, between 0.05 and 300 km. Isofemale lines within sites showed little or no reproductive isolation, but nearly complete isolation among sites. Reproductive isolation was also independent of morphology. These results suggest that the Acanthocyclops population at each site could be considered a distinct cryptic biological species. These copepods expressed morphological stasis – persistence of morphological uniformity despite reproductive isolation. Because of the effect of site and environment on morphology, we recommend using much larger collections (many sites), common garden experiments, and a multi-disciplinary approach (morphological, reproductive, chromosomal, and molecular) as the basis for future taxonomic research on putative copepod species.     

A new species of Atheroides Haliday (Hemiptera,Aphididae) native to North America

We report and describe the first species of Atheroides Haliday presumed to be native to North America, collected at the Valles Caldera National Preserve, New Mexico, USA. We hypothesize its placement among the Siphini based on morphological, phylogenetic analysis and extend the distribution of the genus to the Holoarctic. We expand the key of the known Atheroides to include the new species and discuss the current hypotheses of the geographic distribution of the type species, Atheroides serrulatus Haliday.     

Comparative lectin histochemical analysis of the duodenal glands in various mammals

Composition and histotopography of lectin receptors have been studied in 12 species of mammals with various nutritional specialization: carnivorous, phytophagous and omnivorous. In cells of the duodenal glands of the carnivorous and omnivorous receptors to concanavalin A and lentil lectin (D-mannosoglycans ) are absent and they are present in the glands of the phytophagous animals. In cells of some parts of the glands presence of receptors to soya bean lectin (N-acetyl-D-galactosamine++) is the most characteristic sign of the duodenal glands in the carnivorous and phytophagous animals. Together with certain differences, depending on the nutritional way of the animals, specific peculiarities of lectins binding with glandulocytes of the duodenal glands are demonstrated. The data on rearrangement of the lectin receptors are obtained during the process of cellular differentiation. Presence of N-acetyl-D-galactosamine++ remnants-biding soya bean lectin in composition of oligosaccharide++ chains of glycoconjugates is a sign of low differential degree of the glandular cells. In more differentiated cells concealment in oligosaccharide chains of D-galactose remnants (peanut and castor-oil lectins receptors) by L-fucose, N-acetil-D-glucosamin remnants and sialic acid can have place; this is demonstrated as accumulation of receptors to wheat germ and Laburnum anagyroides lectins in the glandular cells.     

The Megophthalmidia (Diptera,Mycetophilidae) of North America including eight new species

Megophthalmidia Dziedzicki is a small leiine genus (Mycetophilidae) with seven species described from the Neotropics and ten species from the Palearctic region. Two species of Megophthalmidia have been reported for North America. Recent collecting of Mycetophilidae in California and Arizona, however, shows current North American diversity of Megophthalmidia is at least on par to other regions of the world. Eight new species of Megophthalmidia are described here, increasing the number of Nearctic Megophthalmidia species to nine. Included is a particularly atypical member of the genus, M. saskia sp. n., which expands the genus concept of Megophthalmidia. Of the two species previously recorded for North America, only one actually belongs in the genus. Megophthalmidia occidentalis Johannsen, is fully described and illustrated. The other named species, M. marceda (Sherman) is illustrated and transferred to the genus Ectrepesthoneura Enderlein. A lectotype is designated for this species. A key to the species of Megophthalmidia of North America is provided. The biology of these flies is not yet known. Three of the new Megophthalmidia species – M. lenimenta, M. misericordia, and M. radiata – are only known to occur within small protected areas within the California State Park and UC Natural Reserve systems.     

Diversity and relationships of bradyrhizobia from legumes native to eastern North America

DNA sequencing and polymerase chain reaction (PCR) assays with lineage-specific primers were used to analyze the diversity of 276 isolates of Bradyrhizobium sp. nodule bacteria associated with 13 native legumes species in the northeastern United States, representing eight genera in six legume tribes. A PCR screen with two primer pairs in the rRNA region indicated that seven of the legume species were exclusively associated with strains having markers resembling Bradyrhizobium elkanii, while the remaining six host species harbored strains related to both B. elkanii and Bradyrhizobium japonicum. Sequence analysis of 22 isolates for portions of 16S rRNA and 23S rRNA yielded congruent phylogenetic trees and showed that isolates from different legume genera often shared similar or identical sequences. However, trees inferred from portions of two other genes (alpha-ketoglutarate dioxygenase gene (tfdA), the alpha-subunit of nitrogenase (nifD)) differed significantly from the rRNA phylogeny. Thus, for Bradyrhizobium populations in this region, lateral gene transfer events appear to have altered genealogical relationships of different portions of the genome. These results extend the number of likely cases of gene transfer between divergent taxa of Bradyrhizobium (from members of the B. elkanii lineage to the B. japonicum group) and suggest that transfers have also occurred among separate subgroups of the B. elkanii lineage.     

Morphological and histochemical observations on the intestinal epithelium of Ascardia galli (Nematoda: Ascaridida).

The intestinal epithelium of Ascardia galli has been studied with various cytological and cytochemical techniques. It consists of large epithelial cells resting on a thick collagenous basal lamina. Their luminal surface is provided with microvilli. The intestinal cells store considerable amounts of glycogen and neutral lipids. Some intracellular granular inclusions, which stain for proteins, phospholipids and lipoproteins, are distributed throughout the cytoplasm. The brush border is composed of microvilli whereas the outer surface coat consists of saliva resistant PAS-positive material. The detailed histochemical analysis of surface material has revealed that it is composed of nonacetylated acid mucopolysaccharides rich in hyaluronic acid with carboxylate polyanions. The brush border shows intense activities of acid phosphatase and glucose-6-phosphatase, moderate of ATPase, and lipase, weak of 5'-nucleotidase. Acid phosphatase-positive intracellular structures are seen in the intestinal epithelium which form distinct aggregations.     

Mitochondrial DNA and prehistoric settlements: native migrations on the western edge of North America

We analyzed previously reported mtDNA haplogroup frequencies of 577 individuals and hypervariable segment 1 (HVS1) sequences of 265 individuals from Native American tribes in western North America to test hypotheses regarding the settlement of this region. These data were analyzed to determine whether Hokan and Penutian, two hypothesized ancient linguistic stocks, represent biological units as a result of shared ancestry within these respective groups. Although the pattern of mtDNA variation suggests regional continuity and although gene flow between populations has contributed much to the genetic landscape of western North America, some evidence supports the existence of both the Hokan and Penutian phyla. In addition, a comparison between coastal and inland populations along the west coast of North America suggests an ancient coastal migration to the New World. Similarly high levels of haplogroup A among coastal populations in the Northwest and along the California coast as well as shared HVS1 sequences indicate that early migrants to the New World settled along the coast with little gene flow into the interior valleys.     

Morphological, histochemical and immunohistochemical characterization of secretory production of the ciliary glands in the porcine eyelid

In addition to performing general histology and cytology of the ciliary glands of the miniature pig, we studied the localization of glycoconjugates and beta-defensins in these glands with the use of carbohydrate histochemical and immunohistochemical methods. The secretory cells of the glands were equipped with non-homogeneous secretory granules, a well-developed Golgi apparatus and rough endoplasmic reticulum. The secretory epithelium and luminal secretion of the glands contained large amounts of neutral and acidic glycoconjugates with various saccharide residues (alpha-L-Fuc, beta-D-Gal, alpha-D-GalNAc and sialic acid). The sebaceous glands and tarsal glands also exhibited positive reactions to most of the histochemical methods. Additionally, the antimicrobial peptide group of beta-defensins was demonstrated to be products of the ciliary glands, as well as the sebaceous glands and tarsal glands. The results obtained are discussed with regard to the specific function of the ciliary glandular secretions. These secretory products may be related to the moistening and general protection of the skin surface of the eyelid and ocular surface.     

Plant regeneration from cultured leaf explants of eight wild tomato species and two relatedSolanum species

Summary Optimum conditions for plant regeneration from cultured leaf explants were ascertained for eight different wild tomato (Lycopersicon) species and two closely relatedSolanum species. Of the eight media tested, basal MS medium supplemented with 5 μM of the cytokinin 6-benzyladenine proved to be the best overall regeneration medium. Regeneration frequency varied significantly between species with maximum frequency of regeneration observed forL. chilense, L. peruvianum, andS. lycopersicoides.