Primary listerial infections are exacerbated in mice administered neutralizing antibody to macrophage colony-stimulating factor.

The serum and tissue levels of macrophage colony-stimulating factor (M-CSF) are elevated in mice during a primary immunologic response to infection by Listeria monocytogenes. Experiments were performed to determine the specific role of M-CSF in the resolution of listerial infections. The bulk of Listeria injected into a mouse i.v. is deposited in the liver. The expression of M-CSF mRNA in the liver increased markedly within 2 h postinfection. Maximum expression was dependent upon the dose of Listeria inoculated. The administration of anti-M-CSF mAb reduced the percentage of Mac-1+ mononuclear phagocytes subsequently found in the livers of infected animals. This reduction correlated inversely with an increase in the number of Listeria associated with both the parenchymal and NPC populations. These results suggest that M-CSF may play an important role in the primary immunologic response to Listeria in the liver by stimulating the production, mobilization, and/or biologic activity of Mac-1+ mononuclear phagocytes.     

Ovine coccidiosis: the pathology of Eimeria crandallis infection

Doses of sporulated oocysts of Eimeria crandallis ranging from 50 to 300,000,000 were given to 27 housed lambs aged between 4 and 12 weeks that had been reared coccidia-free. Lambs were killed between 1 and 22 days after inoculation and their tissues examined histologically. Clinical effects were very variable and not closely related to inoculating dose. Some lambs showed intermittent diarrhoea, sometimes watery and sometimes containing muco-fibrinous material, either in the form of intestinal casts or as a greyish discoloration. Loss of surface epithelial cells and villus atrophy in the small intestine were associated with first generation meronts and the release of merozoites from them; in some lambs apoptosis of crypt cells also occurred, leading to crypt atrophy. Severe diffuse crypt hyperplasia was associated with pro-gamonts in the small and large intestines. In a minority of the lambs this stage was associated with what appeared to be crypt destruction by host cells in the lamina propria, leading in some cases to denudation and severe diarrhoea.     

CHROMOSOME NUMBERS IN SOUTH AMERICAN HAPLOPAPPUS CASS. (COMPOSITAE)

Chromosome counts are reported for 33 species from all four sections of the genus Haplopappus in South America. These include first reports for 28 species and two putative hybrids. All chromosome numbers reported herein are 2n = 5_II, with the exception of H. prunelloides with 2_n = 6_II. Unlike the North American species, the morphological diversity of South American taxa is not concomitant with chromosomal variation.     

Cryostat Microtomy of Lung Tissue in an Expanded State

A technique is reported for cryostat sectioning of lung tissue in an expanded state for use in viral immunofluorescence studies. A 1: 2 mixture of O.C.T. embedding compound and phosphate-buffered saline is injected intratracheally into fresh lung tissne. The lung tissue is frozen in liquid nitrogen and sectioned with a cryostat. Compared to other published reports of lung sectioning for immunofluorescence miscroscopy, this method has the advantages of bekg easy and quick, maintaining the lung sectiom in an expanded rather than collapsed state and avoiding contact with chemicals potentially capable of altering sensitive viral antigens.     

Epidemic management and control through risk-dependent individual contact interventions

Testing, contact tracing, and isolation (TTI) is an epidemic management and control approach that is difficult to implement at scale because it relies on manual tracing of contacts. Exposure notification apps have been developed to digitally scale up TTI by harnessing contact data obtained from mobile devices; however, exposure notification apps provide users only with limited binary information when they have been directly exposed to a known infection source. Here we demonstrate a scalable improvement to TTI and exposure notification apps that uses data assimilation (DA) on a contact network. Network DA exploits diverse sources of health data together with the proximity data from mobile devices that exposure notification apps rely upon. It provides users with continuously assessed individual risks of exposure and infection, which can form the basis for targeting individual contact interventions. Simulations of the early COVID-19 epidemic in New York City are used to establish proof-of-concept. In the simulations, network DA identifies up to a factor 2 more infections than contact tracing when both harness the same contact data and diagnostic test data. This remains true even when only a relatively small fraction of the population uses network DA. When a sufficiently large fraction of the population (≳ 75%) uses network DA and complies with individual contact interventions, targeting contact interventions with network DA reduces deaths by up to a factor 4 relative to TTI. Network DA can be implemented by expanding the computational backend of existing exposure notification apps, thus greatly enhancing their capabilities. Implemented at scale, it has the potential to precisely and effectively control future epidemics while minimizing economic disruption.     

Evidence for widespread genomic methylation in the migratory locust, Locusta migratoria (Orthoptera: Acrididae)

The importance of DNA methylation in mammalian and plant systems is well established. In recent years there has been renewed interest in DNA methylation in insects. Accumulating evidence, both from mammals and insects, points towards an emerging role for DNA methylation in the regulation of phenotypic plasticity. The migratory locust (Locusta migratoria) is a model organism for the study of phenotypic plasticity. Despite this, there is little information available about the degree to which the genome is methylated in this species and genes encoding methylation machinery have not been previously identified. We therefore undertook an initial investigation to establish the presence of a functional DNA methylation system in L. migratoria. We found that the migratory locust possesses genes that putatively encode methylation machinery (DNA methyltransferases and a methyl-binding domain protein) and exhibits genomic methylation, some of which appears to be localised to repetitive regions of the genome. We have also identified a distinct group of genes within the L. migratoria genome that appear to have been historically methylated and show some possible functional differentiation. These results will facilitate more detailed research into the functional significance of DNA methylation in locusts.