Strains of insect-pathogenic fungi with high virulence toward certain pest insects have great potential for commercial biological control applications. Identifying such strains has been a central theme in using fungi for biological control. This theme is supported by a persistent paradigm in insect pathology which suggests that the host insect is the predominant influence on the population genetics of insect-pathogenic fungi. In this study, a population genetics analysis of the insect-pathogenic fungus Metarhizium anisopliae from forested and agricultural habitats in Ontario, Canada, showed a nonrandom association of alleles between two distinct, reproductively isolated groups (index of multilocus association ‫؍‬ 1.2). Analyses of the mitochondrial DNA showed no differences between the groups. The two groups were associated with different habitat types, and associations with insect hosts were not found. The group from forested areas showed an ability for cold-active growth (i.e., 8°C), while the group from the agricultural area showed an ability for growth at high temperatures (i.e., 37°C) and resilience to UV exposure. These results represent a significant paradigm shift; habitat selection, not host insect selection, drives the population structure of these insect-pathogenic deuteromycetous fungi. With each group we observed recombining population structures as well as clonally reproducing lineages. We discuss whether these groups may represent cryptic species. Worldwide, M. anisopliae may be an assembly of cryptic species, each adapted to certain environmental conditions. The association of fungal genotypes with habitat but not with host insects has implications on the criteria for utility of this, and perhaps other, fungal biocontrol agents.Insect-pathogenic fungi have genetic features related to insect infection (17), and the population genetics of these fungi are also assumed to be influenced primarily by host insect taxa (5,6,14,19,20,24,28,33,35). Metarhizium anisopliae is an insect-pathogenic, haploid, deuteromycetous fungus that is assumed to reproduce clonally, and it is also assumed that certain genotypes are related to an insect host (5,6,14,19,20,24,28,33,35). It also has the potential for parasexual reproduction (36), although an analysis of clonality versus recombination has not been undertaken. One of the distinctive features of a clonal population is the widespread occurrence of identical genotypes (23). Here we have undertaken to determine the population structure of M. anisopliae and to test the paradigm that certain genotypes are related to insect hosts.M. anisopliae is a recognized pathogen of more than 200 insect species, including several major pests (29). It is a recurrent paradigm in the literature that the insect host drives the population structure, i.e., that there are fungal isolates or genotypes adapted for pathogenesis toward certain species or taxa of insects (5,6,14,19,20,24,28,32,35). Because this fungus offers an environmentally safe alternative to chemical pesticides, it is of...

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Solid freeform fabrication (SFF) enables the fabrication of anatomically shaped porous components required for formation of tissue engineered implants. This article reports on the characterization of a three-dimensional-printing method, as a powder-based SFF technique, to create reproducible porous structures composed of calcium polyphosphate (CPP). CPP powder of 75-150 microm was mixed with 10 wt % polyvinyl alcohol (PVA) polymeric binder, and used in the SFF machine with appropriate settings for powder mesh size. The PVA binder was eliminated during the annealing procedure used to sinter the CPP particles. The porous SFF fabricated components were characterized using scanning electron microscopy, micro-CT scanning, X-ray diffraction, and mercury intrusion porosimetry. In addition, mechanical testing was conducted to determine the compressive strength of the CPP cylinders. The 35 vol % porous structures displayed compressive strength on average of 33.86 MPa, a value 57% higher than CPP of equivalent volume percent porosity made through conventional gravity sintering. Dimensional deviation and shrinkage analysis was conducted to identify anisotropic factors required for dimensional compensation during SFF sample formation and subsequent sintering. Cell culture studies showed that the substrate supported cartilage formation in vitro, which was integrated with the top surface of the porous CPP similar to that observed when chondrocytes were grown on CPP formed by conventional gravity sintering methods as determined histologically and biochemically.

This in vitro integration model will allow study of the mechanism(s) regulating cartilage integration. Understanding this process will facilitate enhancement of cartilage repair strategies for the treatment of chondral injuries.

AGEs accumulation due to intra-articular ribose-containing injections in the HGP model of spontaneous knee OA did not enhance disease progression.