The Sugar Content and Density of Living and Dead Microsporidian (Protozoa: Microspora) Spores

• Published in: Journal of invertebrate pathology 1996-01, Vol.67 (1), p.80-91
• Main Authors: Undeen, Albert H., Solter, Leellen F.
• Format: Article
• Language: English
• Subjects: agent pathogene; azucares; azucares reductores; Biochemistry. Physiology. Immunology. Molecular biology; Biological and medical sciences; densidad; densite; density; density gradient, Ludox; Edhazardia aedis; Endoreticulatussp; esporas; estres; Fundamental and applied biological sciences. Psychology; germinacion; germination; Microspora; Microsporidia; Microsporidian spores; Microsporidium; Microsporidium spp; Nosema; Nosema algerae; Nosema apis; Nosema disstriae; Nosema locustae; nutritive value; organismos patogenos; pathogenicity; pathogens; poder patogeno; pouvoir pathogene; Protozoa; reducing sugars; spore; spore sugars; spores; stress; sucre reducteur; sucres; sugars; Thelohania; Thelohania sp; Vairimorpha; Vairimorpha lymantriae; Vairimorpha necatrix; Vairimorpha plodiae; Vairimorpha spp; valeur nutritive; valor nutritivo; viabilidad; viabilite; viability; viability of spores
• ISSN: 0022-2011; 1096-0805
• DOI: 10.1006/jipa.1996.0012

Microsporidian (Microspora) spores were subjected to several kinds of stress: ultraviolet light (Nosema algerae); chilling in ice water (Edhazardia aedis); freezing and thawing, with or without glycerol as a cryoprotectant (Nosema disstriae, Thelohaniasp.); long-term cold storage (Vairimorphaspp.,Endoreticulatussp.,Thelohaniasp., andMicrosporidiumsp.); and extended periods at room temperature (Microsporidiumsp. andVairimorpha lymantriae).N. algeraespores were inactivated by incubation in 0.05mNaCl or 24 hr at 23°C. Viability of the spores was assessed either by infectivity to a susceptible host or byin vitrogermination. Carbohydrates were extracted from the spores for measurement of the total sugars (anthrone reactive) and reducing sugars (Nelson's test), and quantities and ratios of the two classes of sugars were compared. Buoyant density differences associated with sugar concentration and viability changes were estimated by Ludox density gradient centrifugation. Reducing sugar levels increased after germicidal ultraviolet radiation, chilling, or freezing, concurrent with loss of infectivity or capacity for germination. The smaller reducing sugar molecules apparently diffused slowly from the inviable spores, causing a gradual reduction in the total concentration of sugars. Many samples of spores held for long periods in cold storage were almost devoid of sugar. These changes were not seen inN. algeraespores that were temporarily inactivated. In all cases, spores that were severely depleted in carbohydrates had a significantly lower buoyant density. The bands of heavy spores had a mean density ± SE of 1.197 ± 0.010 g/ml and the mean density of the light, sugar-depleted spores was 1.137 ± 0.024 g/ml. These results suggest that, where no other means are possible, sugar concentrations or spore density might be used to assess the viability of spores.