Growth and morphogenesis ofBotrytis cinerea. Effects of exogenous calcium ions,calcium channel blockers and cyclosporin A

Calcium channel blockers, verapamil, nitrendipin and nifedipin, and cyclosporin A inhibited growth of colonies ofBotrytis cinerea in a concentration-dependent manner and simultaneously induced morphological changes of its hyphal tips. Exogenous calcium at the concentration of 100 mmol/L decreased the growth-inhibitory effects of channel blockers and cyclosporin A; however, at the concentration of 500 mmol/L Ca²⁺ their inhibitory effects were increased. At the latter concentration, calcium partly reversed the morphogenic effects of the blockers but not of cyclosporin A.     

The control of flower initiation by gibberellin in Helianthus annuus L. (sunflower), a non-photoperiodic plant

The involvement of gibberellins in the control of flowering of sunflower was studied by direct application of GA₃ to the apex of the plants, analysis of the endogenous levels of gibberellin-like substances at different plant ages, and indirectly by the application of paclobutrazol, an inhibitor of gibberellin synthesis. GA₃ speeded-up flower initiation and floral apex development. The time of GA₃ application was more critical than the amount of GA₃ applied. The endogenous levels of gibberellin-like compounds increased significantly by day 15 after sowing. The application of paclobutrazol markedly delayed floral initiation and this effect was also depedent on plant age. Both GA₃ and paclobutrazol had their greatest effects between 10 and 20 days after sowing suggesting that an increase in gibberellins in that time period plays a role in floral initiation.     

Vasculature of the head and respiratory organs in an obligate air-breathing fish,the swamp eel Monopterus (=Amphipnous) cuchia

Methyl methacrylate vascular corrosion replicas were used to examine the macrocirculation in the head region and the microcirculation of respiratory vessels in the air-breathing swamp eel Monopterus cuchia. Fixed respiratory tissue was also examined by SEM to verify capillary orientation. The respiratory and systemic circulations are only partially separated, presumably resulting in supply of mixed oxygenated and venous blood to the tissues. A long ventral aorta gives rise directly to the coronary and hypobranchial arteries. Two large shunt vessels connect the ventral aorta to the dorsal aorta, whereas the remaining ventral aortic flow goes to the respiratory islets and gills. Only two pairs of vestigial gill arches remain, equivalent to the second and third arches, yet five pairs of aortic arches were identified. Most aortic arches supply the respiratory islets. Respiratory islet capillaries are tightly coiled spirals with only a fraction of their total length in contact with the respiratory epithelium. Valve-like endothelial cells delimit the capillary spirals and are unlike endothelial cells in other vertebrates. The gills are highly modified in that the lamellae are reduced to a single-channel capillary with a characteristic three-dimensional zig-zag pathway. There are no arterio-arterial lamellar shunts, although the afferent branchial artery supplying the gill arches also supplies respiratory islets distally. A modified interlamellar filamental vasculature is present in gill tissue but absent or greatly reduced in the respiratory islets. The macro- and micro-circulatory systems of M. cuchia have been considerably modified presumably to accommodate aerial respiration. Some of these modifications involve retention of primitive vessel types, whereas others, especially in the microcirculation, incorporate new architectural designs some of whose functions are not readily apparent.     

A novel method for the evaluation of proximal tubule epithelial cellular necrosis in the intact rat kidney using ethidium homodimer

Background  

Ethidium homodimer is a cell-membrane impermeant nuclear fluorochrome that has been widely used to identify necrotic cells in culture. Here, we describe a novel technique for evaluating necrosis of epithelial cells in the proximal tubule that involves perfusing ethidium homodimer through the intact rat kidney. As a positive control for inducing necrosis, rats were treated with 3.5, 1.75, 0.87 and 0.43 mg/kg mercuric chloride (Hg²⁺, intraperitoneal), treatments which have previously been shown to rapidly cause dose-dependent necrosis of the proximal tubule. Twenty-four h after the administration of Hg²⁺, ethidium homodimer (5 μM) was perfused through the intact left kidney while the animal was anesthetized. The kidney was then removed, placed in embedding medium, frozen and cryosectioned at a thickness of 5 μm. Sections were permeabilized with -20°C methanol and then stained with 4',6-diamidino-2-phenylindole (DAPI) to label total nuclei. Total cell number was determined from the DAPI staining in random microscopic fields and the number of necrotic cells in the same field was determined by ethidium homodimer labeling.     

The postnatal histology of the epididymis in buffalo (Bubalus bubalis).

The epididymis of buffalo is differentiated into 6 regions. The head represents the first 3 regions, the body the 4th region and the tail the 5th and 6th region. At 3-30 weeks, the epithelium is simple high columnar with few basal cells in region I, simple low columnar with few basal cells in region II, pseudostratified low columnar in regions III, IV, V, and pseudostratified low columar in region VI. As age advances, the epithelium increases in height and shows a tendency toward advanced pseudostratification. The basal cells are greater in number in regions III, IV and V than in the other regions of the epididymis. The epithelial cells contain stereocilia in region I at 3 weeks and regions III, IV and V at 30 weeks, whereas they are absent in regions II and VI. The tubules in region I are the smallest in diameter while the tubules in region VI have the largest diameter.