The electron microscopic study of cell-to-cell interactions between antagonistic microorganisms

The electron microscopic study of thin sections and positively stained specimens of cells taken from particular cocultures of Lactobacillus acidophilus D75, Lactobacillus casei YIT 9018, Shigella flexnery 2a, Bacillus subtilis ATCC 6633, and Staphylococcus aureus ATCC 25923 (some of these bacteria are antagonistic to others) showed the presence of specific ultrastructural elements indicating cell specialization and cooperation. The responses of antagonistic bacteria manifested themselves at the cellular and population levels.     

The effects of simulated rainfall on cochineal insects (Homoptera: Dactylopiidae): colony composition and survival on cactus cladodes

ABSTRACT. 1. A rainfall simulator is described that was used to investigate the effects of rainfall on the cochineal insect Dactylopius opuntiae (Cockerell). This species occurs in discrete colonies that are protected by a copious covering of opaque'woolly'wax, and is the most important biological control agent of the prickly pear cactus, Opuntia ficus-indica (L.) Miller, in South Africa.
2. We record the composition of cochineal colonies (stage and number of individuals) in relation to colony size to allow accurate predictions of colony composition from size measurements of the intact, wax-covered colonies before their exposure to rainfall.
3. Even short exposures (15 min) to simulated rainfall (delivered at a rate of about 50 mm/h) resulted in wax erosion, and the effect was most marked in small, recently established colonies. Coverings of compacted wax protected the mature colonies from erosion.
4. The number of colonies that were washed off the plant was a function of colony size and the duration of exposure to simulated rainfall. Most of the small, recently established colonies were washed from the plants after 120 min. All of the large, mature colonies, albeit badly mutilated and containing far fewer individuals, remained on the plants even after 240 min exposure.
5. Survival of individuals, in colonies of all sizes, was less than about 40% after short bouts of rainfall (30 min). First- and second-instar individuals accounted for most of the observed mortalities, and mortality of all stages increased with increasing rainfall duration.
6. These observations provide a partial explanation for the poor performance of D. opuntiae as a biological control agent of cacti in higher-rainfall areas.     

First record ofPhytoseiulus persimilis (Acari: Phytoseiidae) in Turkey

The predatory mitePhytoseiulus persimilis Athias-Henriot is widely used for biological control of spider mites in greenhouse. Despite its records from various Mediterranean countries,P. persimilis was not recorded from Turkey. Here we report the natural colonies ofP. persimilis observed along the Mediterranean coast of Turkey.     

Diel rhythms of tick parasitism on incubating African penguins

1. Ticks (Ornithodoros capensis Neumann) were most abundant on incubating host African penguins (Spheniscus demersus Linnaeus) at 24.00 hours and least abundant during 09.00-12.00 hours during 4 day periods in May and October at 3 h intervals. 2. Ticks were three times as abundant in May, the start of the breeding season, as in October, at its end. 3. Air temperature and humidity appear less important than light levels in determining tick activity. 4. The degree of tick parasitism of breeding seabirds is best studied at night.     

Dynamics of the growth unit of substrate mycelium in streptomycete colonies

The changes in the length of the growth unit of substrate mycelium (from the hyphal tip to the side branch) in a developing streptomycete colony are assessed as dependent on the colony age as well as on the type and concentration of the limiting substrate.     

An in vitro assay for T lymphocyte progenitors (CFU-preT)

Thy-1.2 negative progenitors give rise to Thy-1.2 positive colony cells when mouse bone marrow is cultured in vitro. The bone marrow cells are immobilized in a viscous medium containing methyl cellulose; discrete colonies are identifiable at 2 days and contain 30–60 cells by day 3 of culture. Colonies are tightly packed spheres (raspberries) and grow suspended in the gel. Growth of the raspberry colonies is absolutely dependent upon the presence of the appropriate serum (horse or human; not fetal calf) and conditioned medium from pokeweed mitogen-stimulated mouse spleen cells. As little as 0.1% of the conditioned medium is sufficient to promote raspberry colony growth. Under these conditions, nude mouse bone marrow yields as many colonies (1 per 1,000 nucleated cells plated) as normal marrow. Thymus, lymph node; and spleen (normal or nude) do not form colonies. Colony precursors are predominantly in S phase of the cell cycle, as determined by tritiated thymidine suicide of fresh bone marrow. Their numbers fall with age. Because the cells in colonies are Thy-1 positive, peanut agglutinin-positive, and active in a pre-T cell synergy assay, we conclude that their precursors are early committed T cell progenitors, and propose that they be called CFU-preT.     

Habitat use by Mountain Plovers in prairie dog colonies in northeastern New Mexico

ABSTRACT Mountain Plovers (Charadrius montanus) are grassland birds that often breed in close association with colonies of black‐tailed prairie dogs (Cynomys ludovicianus). However, not all colonies provide plover nesting habitat or habitat of equal quality, and the characteristics of colonies important for plovers remain poorly understood. Over two years, I used plover distribution surveys, territory mapping, and habitat sampling to study habitat use by plovers in prairie dog colonies in shortgrass prairie in northeastern New Mexico. My objective was to document important components of plover breeding habitat in colonies by comparing characteristics of used and unused habitats at three spatial scales: colony, territory, and nest‐site. I found evidence of plover breeding in 14 of 44 colonies in 2009 and 13 of 43 colonies in 2010. Based on logistic regression, the probability of a colony being occupied by plovers was positively associated with colony size, but negatively associated with mean vegetation height. Preference for larger colonies could relate to minimum habitat requirements, or a potential tendency of this species to nest in social clusters. Shorter vegetation height was strongly correlated with greater bare ground and lower forb/subshrub cover, all characteristics that may be related to plover predator avoidance and foraging microhabitat. At both the territory and nest‐site scale, areas used by plovers had shorter vegetation, more bare ground, and less forb/subshrub cover than unused areas. Nest sites were also more sloped, perhaps to reduce risk of flooding, and located further away from the nearest prairie dog burrow, perhaps to reduce risk of disturbance. Overall, my results show that plover use of prairie dog colonies was influenced by landscape and habitat features of colonies, and suggest that large colonies are particularly valuable because they are most likely to contain adequate areas with preferred habitat characteristics.     

Primary cultures of embryonic rat heart cells

Summary In contrast to neonatal rat heart cells in culture, embryonic myocardial cells form colonies. They also differ from neonatal cells in their appearance and behavior; they have fewer striations, fewer binucleated cells, loose packing and sorting from nonmuscle cells, and most of all a greater capacity to divide. This work was supported in part by Department of Energy Contract EY-76-C-03-0012 and Environmental Protection Agency Contract IAG-D5-E-681-AO. This paper is part of a dissertation submitted by M. J. O. M. in partial fulfillment of the requirement for the Ph.D. degree at the University of California.     

Purification of a human urinary colony-stimulating factor

Colony-stimulating factor (CSF), a protein required for the in vitro formation of colonies composed of granulocytes and/or macrophages, was isolated from the urine of anemic patients by using a seven-step procedure. The purified, homogeneous CSF had a specific activity of 1.9 X 10(8) U/absorbance unit at 280 nm (AU). This represents an overall purification of 25,330-fold and a total recovery of 3.8%. Upon iodination of the protein, the radioactivity migrated on sodium dodecyl sulfate (SDS) gel electrophoresis as a single peak with an apparent molecular weight of 46,000; reduction with mercaptoethanol caused dissociation to a single component of molecular weight 23,000. Only the dimer is active in stimulating colony formation. Urinary CSF stimulates formation of colonies comprising only macrophages in the mouse bone marrow cell culture assay. A neutralizing antibody raised against mouse L-cell CSF did not neutralize the activity of the urinary CSF but did bind it. This may indicate that the relative positions of antibody binding sites and the active sites are different in these two glycoproteins.