Retinoic acid increases the length and volume density of ducts in the rat embryonic pancreas

In this study, the role of all-trans retinoic acid (RA) on the proliferation of rat embryonic pancreas ducts and on the proportion of insulin cells was investigated. All-trans RA (10-6 m) was added to Ham's F12.ITS serum-free medium in which 12.5 day rat dorsal pancreatic buds were cultured on Matrigel. Control explants were cultured on Matrigel in Ham's F12.ITS alone or in Ham's F12.ITS containing ethanol (the diluent for RA). After a 7 day culture period, explants were incubated with bromodeoxyuridine (BrdU) for assessment of cell proliferation. Explants were processed for both morphometry and immunocytochemistry. The length density and volume density of the pancreatic ducts were assessed using an image analysis system. Cells positive for insulin, BrdU and glucagon were localized on adjacent serial sections. RA treatment caused a statistically significant increase in the volume density (P < 0.007) and length density (P < 0.008) of the ducts, as well as a 1.2-fold increase (P < 0.0001) in the proportion of insulin to glucagon cells, compared to both control groups. Few insulin cells were BrdU positive, indicating that cells had a low proliferation rate. The increased proportion of insulin cells may relate to the increased volume density and length density of the ducts in RA-treated explants. It is suggested that RA stimulated the production of additional progenitor cells and not proliferation of existing insulin cells.     

Differential anatomical response of Norway spruce stem tissues to sterile and fungus infected inoculations

The anatomical defense responses in stems of Norway spruce (Picea abies) clones of different resistance to pathogenic fungi were characterized over time and distance from small mechanical wounds or wounds inoculated with the root rot fungus Heterobasidion annosum. Common responses for both treatments included division of ray parenchyma and other cells in the cambial zone, accumulation of phenolic inclusions in ray parenchyma cells, activation of phloem parenchyma (PP) cells, and formation of traumatic resin ducts (TDs) in the xylem. TD formation occurred synchronously from a tangential layer of cells, or symplasmic domain, within the zone of xylem mother cells. TD induction is triggered by a signal, which propagates a developmental wave in the axial direction at about 2.5 cm per day. TDs are formed at least 30 cm above single inoculations within 16–36 days after inoculation. The size and number of TDs is attenuated further away from the inoculation site, indicating a dose-dependent activity leading to TD development. Compared to sterile wounding, fungal inoculation gave rise to more and larger TDs in all clones, and multiple rows of TDs in weak clones. Fungal inoculation also induced the formation of more new PP cells, increasing the number of PP cells in the phloem in the year of inoculation up to 100%. TD and PP cell formation was greater in susceptible compared to resistant clones and after fungal versus sterile inoculation. Potential mechanisms responsible for this variable response are discussed.     

Right-handed penises of the earwig Labidura riparia (Insecta, Dermaptera, Labiduridae): evolutionary relationships between structural and behavioral asymmetries

The number of penises vary in the insect suborder Forficulina (order Dermaptera; earwigs). Males of the families Diplatyidae, Pigidicranidae, Anisolabididae, Apachyidae, and Labiduridae have two penises (right and left), while those of the Spongipohridae, Chelisochidae, and Forficulidae have a single penis. The proposed phylogenetic relationships among these families suggest that the single‐penis families evolved from an ancestor possessing two penises. To date, examinations of double‐penis earwig species have found that only a single penis is used per single copulation. These diversities in structural and behavioral aspects of genitalia raises the following intriguing questions: How are the two penises used? Why did a penis degenerate in several earwig families, and which one was lost? To address these questions, structural and behavioral asymmetries were examined in detail for a representative species Labidura riparia (Labiduridae). Although there was no detectable morphological differentiation between the right and left penises, male L. riparia predominantly used the right one for insemination. This significant “right‐handedness” developed without any experience of mating and was also manifested in the resting postures of the two penises when not engaged in copulation. However, surgical ablation of the right penis did not influence the insemination capacity of males. In wild‐caught males, only about 10% were left‐handed; within this group, abnormalities were frequently observed in the right penis. These lines of evidence indicate that the left penis is merely a spare intromittent organ, which most L. riparia males are likely never to use. Additional observations of five species of single‐penis families revealed that the left penis degenerated in the common ancestor of this group. Considering the proposed sister relationship between the Labiduridae and the single‐penis families, it is possible that such behavioral asymmetries in penis' use, as observed in L. riparia, are parental to the evolutionary degeneration of the infrequently used left penis. J. Morphol., 2006. © 2006 Wiley‐Liss, Inc.     

Expression and localization of regenerating gene I in a rat liver regeneration model

Regenerating gene (Reg) I has been identified as a regenerative/proliferative factor for pancreatic islet cells. We examined Reg I expression in the regenerating liver of a rat model that had been administered 2-acetylaminofluorene and treated with 70% partial hepatectomy (2-AAF/PH model), where hepatocyte and cholangiocyte proliferation was suppressed and the hepatic stem cells and/or hepatic progenitor cells were activated. In a detailed time course study of activation of hepatic stem cells in the 2-AAF/PH model, utilizing immunofluorescence staining with antibodies of Reg I and other cell-type-specific markers, we found that Reg I-expressing cells are present in the bile ductules and increased during regeneration. Reg I-expressing cells were colocalized with CK19, OV6, and AFP. These results demonstrate that Reg I is significantly upregulated in the liver of the 2-AAF/PH rat model, accompanied by the formation of bile ductules during liver regeneration.     

果胶酶的细胞化学定位：马尾松树脂道发生的细胞化学证据

运用薄切片和电镜细胞化学方法观察了马尾松(Pinus massoniana Lamb.)茎皮层树脂道的发育及发育过程中果胶酶的变化。树脂道的发育过程一般可分为4个阶段,即原始细胞阶段、胞间隙形成阶段、腔道扩大阶段和树脂道成熟阶段。在原始细胞阶段,果胶酶的反应产物首先出现在原始细胞膨胀的细胞壁角隅处,然后沿细胞壁中层分布。胞间隙形成后,果胶酶的反应产物分布在细胞壁和胞间隙的交界面。随着胞间隙的扩大,反应产物的密度逐渐降低。当树脂道成熟后,上皮细胞壁上则没有果胶酶的反应产物出现。细胞化学证据表明: 在树脂道的发育过程中,果胶酶降解树脂道原始细胞细胞壁中层,支持树脂道以裂生方式形成。果胶酶的细胞化学定位技术还可用于其他植物中与果胶水解有关的发育过程。     

The effect of variation in light and nitrogen on growth and defence in young Sitka Spruce

1. Young plants of a northern (Alaska) and southern (Oregon) provenance of Sitka Spruce, Picea sitchensis , were subject to high and low light and high and low nitrogen treatments in a polyhouse experiment. The effect of treatments on growth, needle and resin duct size, water content and concentration of quantitative defences (resin and polyphenols), sugars and nitrogen in needles, stems and roots was determined.
2. Concentrations of resin, polyphenols and carbohydrates were higher in low nitrogen treatments as predicted by resource-availability models of defence and the changes were similar in all parts of the trees including roots and in tissues formed prior to experimental treatments. Variation in the relative concentration of resin and polyphenols between tissues may indicate a defensive trade-off. The size of needle resin ducts was positively correlated with tree growth but no evidence for 'structural' limitation of resin concentration in needles was found.
3. Changes in concentration of quantitative defences did not appear to be the result of a direct trade-off with growth but reflected treatment-induced variation in the root/shoot ratio. Production of quantitative secondary chemicals may therefore be part of an integrated response of the trees to environmental stress.
4. Bioassays with Elatobium abietinum, Gilpinia hercyniae and the fungus Phacidium coniferarum showed that changes in needle size, the nutritional and water content of tissues and the balance between nutrients and secondary chemicals influenced performance of one or more of the organisms. Changes in the concentration of carbon-based secondary chemicals alone were, therefore, of only limited value in predicting susceptibility of Spruce to insects and fungi.     

Orthogonal-polarization-gating optical coherence tomography for human sweat ducts in vivo

We propose an orthogonal-polarization-gating optical coherence tomography (OPG-OCT) for human sweat ducts in vivo. OPG-OCT is composed of the orthogonal linearly polarized light of a sample arm individually interfering with orthogonal linearly polarized lights of the reference arms, where OPG-OCT induces two images, one reflecting the projection intensity and the other the horizontal linear diattenuation (HLD). The results demonstrate that OPG-OCT projection intensity could improve the image quality of sweat ducts. HLD also clearly illustrates the spiral shape of the sweat ducts. Finally, sweat ducts in intensity image are segmented by employing convolutional neural networks (CNN). The proportions of left-handed and right-handed ducts are extracted to characterize the sweat ducts based on HLD. Therefore, the OPG-OCT technique employing CNN for the human sweat glands has the potential to automatically identify the human sweat ducts in vivo.     

Comparative histochemical localization of secondary metabolites in seed-raised and in vitro propagated plants of Excoecaria agallocha Linn. (Euphorbiaceae), the milky mangrove tree of historical significance

Abstract

Mangroves synthesize novel secondary chemicals that are poorly understood. Among the euphorbiaceous mangrove species, Excoecaria agallocha Linn. produces novel terpenoids and alkaloids of medicinal importance. We conducted a comparative tissue level histochemical study of E. agallocha L. to determine whether in vitro propagation alters the content of phytochemicals within the plant parts. Transverse sections of the root, stem and leaves of seed-raised saplings and in vitro propagated plants stained with 10% vanillin-perchloric acid revealed accumulation of terpenoids in the cork cambium. Alkaloids were localized using Dragendorf's reagent in the cortex of the root sections as brown layers. Methylene blue staining revealed that seed-raised plants possessed more lignified cells, distinct latex ducts and ellipsoidal guard cells compared to the plants propagated in vitro, which revealed abnormal, circular guard cells. The phytochemical content of E. agallocha propagated by the in vitro method was comparable to the seed-raised plants. Phytochemical studies of the species of E. agallocha propagated in vitro would confirm whether the species could be used for its medicinal compounds.     

A multiductal system conveys digestive enzymes from the pancreas into the intestine in the Atlantic salmon

Light microscopic and scanning electron microscopic studies present strong evidence for a multiductal system conveying digestive enzymes from the exocrine pancreas into the anterior intestine in Atlantic salmon.