Observations on rodlet cells found in the vascular system and extravascular space of angelfish (Pterophyllum scalare scalare)

In the angelfish ( Pterophyllum scalare scalare ) numerous rodlet cells were found in the large post-orbital blood vessel caudal to the eye and in the surrounding extravascular space. Within the vessel the rodlet cells formed striking regular arrays, along the inner aspect of the wall. The rodlets within the cells were positive to PAS but negative to Sudan Black B, Masson's, and the Fuelgen stain. The capsule around the cells was negative for all these stains. These rodlet cells appeared to be traversing the vessel endothelium, and to be pushing the endothelium aside without damaging it. Some discharged their contents into the vessel, but we never observed the release of intact rodlets. The nuclei of rodlet cells in actual contact with the vessel were at the end of the cell more distant from the endothelial wall. Cell-to-cell adhesion structures or communications junctions between rodlet cells and the endothelium were not evident. A putative rodlet cell precursor in the extravascular space contained large electron-dense granules, and extended pseudopodia that contacted nearby rodlet cells. Based on their morphology, tissue distribution, and their behaviour, we conclude that the rodlet cell is an endogeneous teleost cell type, and possibly represents a form of matured granulocyte.     

Preparation of peroxidase: antiperoxidase (PAP) complexes for immunohistological labeling of monoclonal antibodies

The production of mouse peroxidase:antiperoxidase (PAP) complexes suitable for immunohistological use in conjunction with monoclonal antibodies is described. Three approaches were explored: 1) production of conventional polyclonal PAP complexes; 2) conversion of rabbit PAP to "pseudo-mouse PAP" by incubation with monoclonal mouse anti-rabbit immunoglobulin; 3) formation of PAP complexes from monoclonal mouse antiperoxidase. PAP complexes prepared by the latter technique gave the best immunohistological labeling reactions, being stable on storage and compatible with a wide range of human monoclonal antibodies. Gel filtration revealed that monoclonal PAP is of lower molecular weight than conventional PAP complexes (fulfilling theoretical predictions based on the monospecificity of monoclonal antibodies).     

MSC-DC interactions: MSC inhibit maturation and migration of BM-derived DC

BACKGROUND: Mesenchymal stromal cells (MSC) comprise one of the BM stromal cells that are known to support hematopoiesis. It has also been suggested recently that MSC display immunosuppressive capacities through inhibiting the differentiation of monocyte-derived DC. DC travel to the lymph nodes (LN) to present Ag to T cells, and CCL21 is the chemokine that plays an important role in DC migration into the T-cell area of LN. We addressed the effect of MSC on this chemotactic activity of DC, one of the typical characteristics upon maturation. METHODS: BM cells were isolated and then cultured for generation of myeloid DC in the presence of GM-CSF and/or lipopolysaccharide with or without MSC. MSC were identified by flow cytometry of the immunologic markers and by performing colony-forming unit fibroblast assay. Migration of DC was observed with a newly developed time-lapse video microscopic technique. RESULTS: MSC co-culture inhibited the initial differentiation of DC, as well as their maturation. The matured DC actively migrated directionally in response to CCL21, a powerful DC-attracting chemokine, whereas the MSC co-cultured DC did not. DISCUSSION: Collectively, the findings of these experiments raise the possibility that MSC suppress the migratory function of DC and so they may serve immunoregulatory activities through the modulation of the Ag-presenting function of DC.     

The resilience and functional role of moss in boreal and arctic ecosystems

CONTENTS: Summary 49 I. Mosses in the northern, high-latitude region 50 II. The role of moss in ecological resilience 51 III. Response of moss to disturbance 54 IV. Future research needs 60 V. Conclusions 62 Acknowledgements 62 References 62 SUMMARY: Mosses in northern ecosystems are ubiquitous components of plant communities, and strongly influence nutrient, carbon and water cycling. We use literature review, synthesis and model simulations to explore the role of mosses in ecological stability and resilience. Moss community responses to disturbance showed all possible responses (increases, decreases, no change) within most disturbance categories. Simulations from two process-based models suggest that northern ecosystems would need to experience extreme perturbation before mosses were eliminated. But simulations with two other models suggest that loss of moss will reduce soil carbon accumulation primarily by influencing decomposition rates and soil nitrogen availability. It seems clear that mosses need to be incorporated into models as one or more plant functional types, but more empirical work is needed to determine how to best aggregate species. We highlight several issues that have not been adequately explored in moss communities, such as functional redundancy and singularity, relationships between response and effect traits, and parameter vs conceptual uncertainty in models. Mosses play an important role in several ecosystem processes that play out over centuries - permafrost formation and thaw, peat accumulation, development of microtopography - and there is a need for studies that increase our understanding of slow, long-term dynamical processes.     

Sugars in the gut of the sandfly Phlebotomus orientalis from Dinder National Park, Eastern Sudan

The sandfly Phlebotomus orientalis Parrot (Diptera: Psychodidae) is the vector of visceral leishmaniasis in eastern and Upper Nile regions of Sudan, where vector infection rates of over 7% have been reported. Sugars are known to be important for development of the parasite and for increasing the survival and oviposition rates of several species of sandflies. In the present study we have analysed the sugars present in the guts of individuals and groups of male and female P. orientalis and compared these with sugars from several potential local plant sources: Acacia seyal, Balanites aegyptiaca and Combretum kordofanum. The distribution of these trees in Sudan is closely correlated with that of P. orientalis. Only 20% of individually analysed female sandflies had significant amounts of sugars present suggesting that P. orientalis either digest their sugar meal quickly or do not require regular sugar meals. Interestingly, the sugars present in the males were significantly different to those found in the females, indicating that they had fed on different sugar sources. There was evidence that fruit sugars from Balanites aegyptiaca, Combretum kordofanum and aphid or coccid honeydew are utilized by male and female P. orientalis. There was evidence to indicate that female P. orientalis feeds directly on honeydew. There was no evidence to indicate that direct feeding on leaves is a typical source for the sugar meal. There was no melizitose and only a very small amount of turanose present in the male, suggesting that honeydew was not an important sugar source for males.     

Nurse bees support the physiological development of young bees (Apis mellifera L.)

Newly emerged worker honeybees (focal bees) were caged individually for 8 days either isolated or together with one companion bee of known age (2–30 days) taken from a colony. The companion bee was replaced every 2nd day. After 8 days, various parameters were investigated in the focal bees as indicators of the level of development. Focal bees which had been caged with 6-day-old companion bees were better developed than isolated focal bees, newly emerged bees, or focal bees caged with almost all other ages of companion bees. They had hypopharyngeal glands that were larger and contained more protein, their thoraces had a higher protein content, and they had a higher rate of proteolytic activity in the midgut. Although the focal bees were supplied with pollen as well as honey, they consumed only small amounts of pollen. We attribute their better development to their having been fed worker jelly by the accompanying companion bees. The 6-day-old companion bees consumed high quantities of pollen and spent more time (18.7 ± 11.85 s/h) feeding focal bees than 12-day-old bees (6.5 ± 4.09 s/h) or foragers (no feeding of focal bees). The results show that even under such artificial conditions, the exchange of food (trophallaxis) promotes the development of young honeybee workers. Accepted: 26 February 1999     

Performance of some elite potato cultivars under abiotic stress at North Sinai

The current experiment was adopted during the summer 2018, fall 2018/2019 and summer 2019 respectively at the Experimental Farm of Baloza station, Desert Research Center. North Sinai Governorate, Egypt to study the effect of different doses of irradiation (0, 20, 30 and 40 Gy), three irrigation levels (100, 80 and 60% field capacity on growth, yield and its quality of some potato cultivars (Spunta, Cara, Caruso and Hermes). Treated Spunta cultivar pre planting with 20 (Gy) and irrigated with 80% field capacity was the best treatment for increasing number of aerial stem/plants, leaf area, total chlorophyll in leaves, average tuber weight, and total yield/fed. Hermes cultivar with 20 (Gy) and irrigation level of 80% was the best for increasing dry matter content in tuber in both mutagenic generations.     

Ultrastructural localization of human complement C3b receptors in the human kidney as determined by immunoperoxidase staining with the monoclonal antibody C3RTo5

The precise localization of human complement C3b receptors in human kidneys was investigated by means of indirect immunoperoxidase staining of frozen kidney sections with the monoclonal antibody C3RT05, which is specific for human C3b receptors. Transmission electron microscopy indicated that C3b receptors are located on the entire cell membrane of the visceral epithelial cells of the glomeruli.