Observations of Microsporum canis with cryoscanning and scanning electron microscopy

The observations of Microsporum canis with cryoscanning and scanning electron microscopy without fixation and dehydration were reported. In the former an almost native state was observed through showing some fuzzy outlines due to frost; in the latter it was shown that marked shrinkage and distortion had occured. There were many granules on the surface of the macroconidia though their function is uncertain.     

井上蛀果斑螟触角感器的扫描电镜观察

利用扫描电镜对井上蛀果斑螟Assarainouei Yamanaka雌雄成虫触角及触角感器的超微结构、类型和分布进行详尽观察。结果表明,井上蛀果斑螟触角上主要分布有9种类型的感器,其中毛形感器2种,锥形感器、刺形感器、耳形感器、腔锥形感器、腔乳头状感器、鳞形感器及Bohm氏鬃毛均1种。其中的腔乳头状感器只在雌虫触角上有分布,雄虫触角鳞形感器及末端毛形感器的数量均多于雌虫。     

Observations of sporulation in Fonsecaea and Phialophora by scanning electron microscopy

An extracellular lipase produced by Thermomyces lanuginosus in palm fruit chaff infusion broth at 45 °C after 6 days of incubation was purified by a combination of ultrafiltration, ethanol precipitation and fractionation on DEAE-cellulose and gel-filtration on Sephadex G.200. A single peak of lipase activity with a tenfold increase in the activity of the enzyme was obtained. The partially purified T. lanuginosus lipase had a recovery value of 25%. Attempts to purify this enzyme further led to an almost complete loss of activity. The lipase had a pH optimum of 6.5 and peak activity at 40 °C. It readily hydrolysed both natural and synthetic triglycerides at 40 °C with optimal activities recorded on palm oil and triolein respectively.     

Effects of iron and chelation on Lake Kinneret bacteria

The response of natural populations of bacteria (prepared by passing Lake Kinneret water through 1 m filters) to additions of Fe²⁺ and/or the chelator ethylenediaminetetraacetic acid (EDTA) was followed by measuring the incorporation of ³H-thymidine into >0.2 m particulates, and also by determining the increments in cell numbers after 24 h. In most cases, a stimulation of ³H-thymidine incorporation was observed in supplemented samples relative to untreated controls after 3 and 24 h incubation. The increase in bacterial numbers was also enhanced by these supplements. Generally, EDTA alone evoked a greater stimulation than Fe²⁺; combined supplements gave no further increase. This response pattern appeared consistently throughout the year in samples taken from near-surface lake waters. These results suggest that the availability of iron or chelators may play an important role in regulating bacterial metabolism and growth even in aquatic ecosystems like Lake Kinneret where ambient concentrations of total Fe are relatively high. Offprint request to: T. Berman.     

悬铃木方翅网蝽触角感器扫描电镜观察

利用扫描电镜对悬铃木方翅网蝽Corythucha ciliata(Say)雌、雄成虫触角背面和腹面进行观察。结果表明:悬铃木方翅网蝽触角为棒状,共4节,分为柄节、梗节和鞭节。触角上共有4种感器,分别为刺型感器、锥形感器、毛型感器和芽型感器;这些感器不存在性二型现象。其中,刺型感器分为大刺型感器和小刺型感器2种类型;芽型感器首次在异翅亚目昆虫触角上发现。雄成虫触角感器数量明显多于雌成虫,不同类型的感器在触角各节上的数量与分布各不相同。     

中国海区几种隐藻类鞭毛藻的扫描电镜观察

报道了来自香港吐露港、中国长江口及厦门港的3个属的3种隐藻及1个变种, 即半片藻Hemiselmis sp. Novarino、伸长斜片藻Plagioselmis prolonga Butcher ex Novarino, Lucas ＆ Morrall、伸长斜片藻北方变种Plagioselmis prolonga var. nordica Novarino, Lucas ＆ Morrall、尖尾全沟藻Teleaulax acuta （Butcher） Hill, 并对每个种类的分类特征、生态分布进行描述, 同时提供每个种的光镜和扫描电镜照片。其中, 半片藻属Hemiselmis Parke是中国海区首次记录的属, 而伸长斜片藻Plagioselmis prolonga和尖尾全沟藻Teleaulax acuta可以引发赤潮。     

Nucleopolyhedrovirus: scanning electron microscopy technique

A simplified methodology was developed to study the geometric form of multiple Bombyx mori Nucleopolyhedrovirus by scanning electron microscopy. The virus belongs to Baculoviridae family and was isolated from the silkworm Bombyx mori (L.) (Lepidoptera: Bombycidae). The polyhedra of Nucleopolyhedrovirus were obtained from the filtrate, inoculum and hemolymph of the silkworm experimentally infected with nuclear polyhedra. This material was placed on stubs, where a copper tape was previously adhered. After dry at room temperature the virus was covered with carbon and gold. Scanning electron microscopy analysis revealed a well defined morphology for the polyhedra of multiple Bombyx mori Nucleopolyhedrovirus, making possible the mathematical study that identified it as a truncated octahedron. The form of the polyhedron can present taxonomic value, once it is specific for each viral lineage.     

Immunolatex localization by scanning electron microscopy of intestinal bacteria from cockroaches.

An immunolatex reagent was developed from antiserum to Fusobacterium varium, an obligate anaerobe isolated from the colon of the cockroach, Periplaneta americana L. A new technique that enabled the preparation of a highly efficient immunolatex conjugate was used to localize the bacterium with scanning electron microscopy, in situ, in the mixed gut contents.     

Unique advantages of using low temperature scanning electron microscopy to observe bacteria

Summary Electron microscopy (EM) has greatly helped to elucidate our understanding of bacterial structure and function. However, several recent studies have cautioned investigators about artifacts that result from the use of conventional EM preparation procedures. To avoid these problems, the use of low temperature scanning electron microscopy (LTSEM) was evaluated for examining frozen, fully hydrated specimens. Spinach leaves (Spinacia oleracea L. cv. New Jersey), which were naturally infected or inoculated with bacteria, were used as the experimental material. 1 cm segments of the infected leaves were plunge frozen in liquid nitrogen, transferred to a cryochamber for sputter coating and then moved onto a cryostage in an SEM. After observation, some of the frozen, hydrated leaf segments were transferred onto agar medium to determine whether preparation for LTSEM was nondestructive to the bacteria. The other tissue segments were chemically fixed by freeze-substitution. The results indicated that after cryopreparation and observation in the LTSEM: (i) viable bacteria, which were recovered from the leaf sample, could be cultured on agar medium for subsequent study, and (ii) the frozen samples could be freeze substituted and embedded so that transmission electron microscopic (TEM) observations could be carried out on the same specimen. In conclusion, frozen, hydrated leaf tissue infected with bacteria can be observed using LTSEM and then can be either processed for TEM observation to obtain further structural details or recovered to culture the pathogenic bacteria for supplementary studies.Abbreviations EPS extracellular polysaccharide - EM electron microscopy - LTSEM low temperature scanning electron microscopy - SEM scanning electron microscopy - TEM transmission electron microscopy - TSA tryptic soy agar - TSB tryptic soy broth Dedicated to Professor Eldon H. Newcomb in recognition of his contributions to cell biology     

Comparison of flow cytometry and epifluorescence microscopy for counting bacteria in aquatic ecosystems.

Flow cytometry was used to count bacterial cells from diverse origins: one strain of E. coli, one sample of lake water, and 18 samples of estuary water. To verify the accuracy and the precision of this technique, total bacteria counts made by flow cytometry were compared with counts by direct observation using epifluorescence microscopy. The results of this study showed that flow cytometry was a reliable technique for counting a mixture of bacteria in samples from aquatic ecosystems.     

Autoradiographic screening for potential heterotrophs in natural algal populations of Lake Kinneret

Microautoradiography was used to screen natural phytoplankton populations from Lake Kinneret for their ability to take up radioactive organic substrates (glucose, acetic acid, amino acids, and glycollic acid. Several of the important Chlorophyta (Pediastrum spp.,Actinastrum hantzschii, Kirchncriella spp.,Coelastrum spp.,Scenedesmus spp., andTetraëdron spp.) and Cyanophyta (Microcystis spp.,Merismopedia sp.,Chroococcus spp., andAnabaena spp.) showed consistent organic uptake. However, the principal bloom former, the dinoflagellatePeridinium cinctum fawestii and most of the pelagic algae observed, never assimilated any of the above substrates. Autoradiographic surveys permit rapid screening of algal populations for species which are capable of taking up organic matter and can indicate potential facultative heterotrophs.     

Rapid selective enumeration of bacteria in foods using a microcolony epifluorescence microscopy technique

The growth patterns of macrocolonies of 59 different pure cultures were studied on eight selective solid media. A method of growing microcolonies on the surface of polycarbonate membrane filters, placed on the selective agar media, followed by staining and examination by epifluorescent microscopy was developed. The patterns of growth of the pure cultures as microcolonies were studied on the eight selective media. Only four media proved to be reliable for this purpose and the relationship between the microcolony count and plate count was studied on these media together with nutrient agar. Microcolony counts using three of these media (enriched lauryl sulphate aniline blue, pseudomonas selective agar (C-F-C) and Baird-Parker medium) were capable of giving reliable estimates of coliforms (r = 0·89), pseudomonads (r = 0·93) and staphylococci (r = 0·92) after incubation at 30°C for 3 or 6 h (staphylococci) at contamination levels of above 10³ bacteria/g in a variety of foods. The results are available within a working day and should allow the more efficient management of food supplies.     

Microcolony epifluorescence microscopy for selective enumeration of injured bacteria in frozen and heat-treated foods

A rapid (less than 6 h) method for selectively enumerating coliforms, pseudomonads, and staphylococci has been developed which involves counting microcolonies grown on the surface of polycarbonate membranes under selective conditions. The method was not directly applicable to foods containing injured bacteria due to the poor formation of or an inability to form microcolonies under selective conditions. However, the introduction of a 3- to 5-h resuscitation step in tryptone soya broth allowed the method to give reliable estimates of these organisms in a variety of frozen and heat-processed foods. Under nonselective conditions, i.e., for total counts, the microcolony method enabled a rapid count to be made of viable bacteria in heat-treated foods, but these results were also made more consistent by the introduction of a resuscitation step. This method makes results from these foods available far faster than conventional enumeration methods.     

Use of nitrocellulose Synpor filters for counting soil bacteria by epifluorescence microscopy

A modified acridine orange staining method for estimating soil bacterial numbers by epifluorescence microscopy using Synpor filters (VCHZ Synthesia, Czechoslovakia) was elaborated. Comparing with the method of direct count of soil bacteria estimated in a Bürker chamber higher counts of bacteria and a lower variation of results were obtained. To verify the sensitivity of the method, microflora from various soil horizons was tested.