Masseter muscle gene expression in relation to various craniofacial deformities: a genotype-phenotype study

Craniofacial form is defined by a number of factors. A major contributor is the jaw musculature especially of the masseter muscle, as differences in transcription and translation of various genes have been documented from this tissue. Up to this point however, no reliable biological predictors of form have been identified. The aims of this study were therefore, to describe the transcriptome of the masseter muscle using microarray technology and to establish and correlate the expression levels of potential candidate and known “informative” genes in masseter muscle with selected clinical, radiographic and dental features of subjects with a variety of craniofacial morphologies. A total of 29 patients (18 deformity and 11 control) were selected from the orthodontic/orthognathic clinics at the Eastman Dental and Whipps Cross Hospitals, London, and Riyadh Military Hospital, Saudi Arabia. Microarray results indicated five “novel” genes not previously reported in relation to the masseter muscles of subjects with variable craniofacial morphologies. Two genes (KIAA1671 and DGCR6) were down-regulated in long face patients, one (SERGEF) was down-regulated in Class III patients and one (LOC730245) was up-regulated in Class II long faces and in all Class III subjects, compared to controls. Another gene (NDRG2) was down-regulated in Class II compared to Class III individuals. Subsequent quantitative Reverse Transcriptase PCR results strongly confirmed that the “novel” gene SERGEF was down-regulated in relation to the clinical, dental and radiographic features of subjects with Class III appearance. SERGEF gene had a positive relationship to the number of dental occlusal contacts and ANB angle. The “informative” gene MHC7 was strongly related to both vertical and horizontal facial deformities. These data suggest that the expression profiles of a number of genes can be analysed and used to make assessments as to their role in the primary aetiology and successful or unsuccessful treatment of patients with specific craniofacial morphologies

Human selection and the relaxation of legume defences against ineffective rhizobia

Enforcement mechanisms are thought to be important in maintaining mutualistic cooperation between species. A clear example of an enforcement mechanism is how legumes impose sanctions on rhizobial symbionts that fail to provide sufficient fixed N2. However, with domestication and breeding in high-soil-N environments, humans may have altered these natural legume defences and reduced the agricultural benefits of the symbiosis. Using six genotypes of soya beans, representing 60 years of breeding, we show that, as a group, older cultivars were better able to maintain fitness than newer cultivars (seed production) when infected with a mixture of effective and ineffective rhizobial strains. Additionally, we found small differences among cultivars in the ratio of effective : ineffective rhizobia released from their nodules, an indicator of future rhizobial strain fitness. When infected by symbionts varying in quality, legume defences against poor-quality partners have apparently worsened under decades of artificial selection