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Summary Background The cleavage-stage mouse embryo is composed of superficially equivalent blastomeres that will generate both the embryonic inner cell mass (ICM) and the supportive trophectoderm (TE). However, it remains unsettled whether the contribution of each blastomere to these two lineages can be accounted for by chance. Addressing the question of blastomere cell fate may be of practical importance, because preimplantation genetic diagnosis requires removal of blastomeres from the early human embryo. To determine whether blastomere allocation to the two earliest lineages is random, we developed and utilized a recombination-mediated, noninvasive combinatorial fluorescent labeling method for embryonic lineage tracing. Results When we induced recombination at cleavage stages, we observed a statistically significant bias in the contribution of the resulting labeled clones to the trophectoderm or the inner cell mass in a subset of embryos. Surprisingly, we did not find a correlation between localization of clones in the embryonic and abembryonic hemispheres of the late blastocyst and their allocation to the TE and ICM, suggesting that TE-ICM bias arises separately from embryonic-abembryonic bias. Rainbow lineage tracing also allowed us to demonstrate that the bias observed in the blastocyst persists into postimplantation stages and therefore has relevance for subsequent development. Conclusions The Rainbow transgenic mice that we describe here have allowed us to detect lineage-dependent bias in early development. They should also enable assessment of the developmental equivalence of mammalian progenitor cells in a variety of tissues.

The generation of T cell receptor (TCR) sequence diversity can produce ‘forbidden’ clones able to recognize self-antigens. Here, the structure of the complex between a myelin basic protein peptide (MBP85–99), human leukocyte antigen (HLA)-DR2 (DRB1*1501/DRA) and TCR-Ob.2F3, the dominant autoimmune clone obtained from a multiple sclerosis (MS) patient, has been determined using structural docking simulation and dynamics in silico and compared to the structure of TCR-Ob.1A12 complexes with the same MHC/peptide determined by X-ray crystallography. The two TCRs differ by three amino acids in the CDR3 α and β loops. As the result different hydrogen bonds are formed between the two CDR3β loops and the peptide in the complexes of the simulated structures, with three hydrogen bonds seen in the TCR-Ob.2F3 complex and five in the TCR-Ob.1A12 complex. The two TCRs, each located near the N-terminal end of the HLA-DR2 binding groove and both had an orthogonal binding axis but they deviated by about 10°. Simulation methods, such as structural docking and molecular dynamics as used here, provide an avenue to understand molecular binding mode efficiently and more rapidly than obtaining multiple crystal structures when a large structural database is already available.

The susceptibility to type 2 diabetes (T2D) involves genetic factors. We studied the distribution of KIR and MHC class I ligands phenotype and genotype frequencies, as well as immunoglobulin KM and GM allotype frequencies in a group of patients (N = 95) with T2D and ethnically matched healthy controls (N = 74) with Puerto Rican ethnic background. We found a slight increase of the 2DL3/2DL3 homozygous genotype in T2D. Moreover, the association between 2DL3/2DL3 genotype was significant in the presence of 2DS4 (pC = 0.01). Also, we observed an epistatic effect of the interaction of 2DL3/2DL3, 2DS4 with allele z of G1M in T2D (pC = 0.004, OR = 3.60, 95% CI, 1.62-8.10). This genetic interaction between KIR and G1M allotypes, associated with T2D, was also significant by multiple logistic regression analysis (p < 0.0001, OR = 4.90, 95% CI, 2.12-11.3). We did not detect population stratification using unlinked short tandem repeat (STR) markers, demonstrating that the patients and controls were ethnically matched. Hence, we have demonstrated in this study an epistatic interaction between KIR genes and the G1M allotype that influences the susceptibility to T2D in Puerto Rican Americans. Our findings are important for understanding the autoimmune or innate immune inflammatory-mediated mechanisms involved in the pathogenesis of T2D.

Copolymer 1 (Cop 1, poly [Y, E, A, K]) is a random synthetic amino acid copolymer effective in the treatment of relapsing forms of multiple sclerosis (MS), a disease that is linked to HLA-DR2 (DRB1∗1501). In the present study various peptides, synthesized according to the binding motifs for both the immunodominant epitope of myelin basic protein (MBP) 85-99, a candidate autoantigen in MS, and Cop 1, differentially inhibited binding of these antigens to disease-associated HLA-DR2 (DRB1∗1501) molecules. In particular, two peptides with residue K at position P-1, as referred to MBP 85-99, inhibited effectively the binding of both biotinylated MBP 85-99 and Cop 1 to HLA-DR2 molecules as well as IL-2 production by two MBP-specific HLA-DR2-restricted T-cell clones. These findings suggest the possible utility of these compounds or their more stable derivatives in treatment of MS.

Campylobacter jejuni is the most common food borne bacterial pathogen and leading cause of food borne disease in humans in the United States and other industrialized nations. Approximately four million cases of human campylobacteriosis occur each year in the United States. Although the majority of cases consist of limited diarrheal illness, severe sequelae can affect a small portion of patients with campylobacteriosis that may include reactive arthritis and Guillain-Barre syndrome. Animal reservoirs primarily include poultry (C. jejuni) and swine (C. coli). Pathogen reduction during poultry processing and safe handling of raw poultry in the kitchen are needed to prevent illness.

There is a need to control the intestinal colonization of broiler chickens by salmonellae in order to reduce the contamination of poultry products. A two-step treatment of broiler chicks with a mucosal competitive exclusion culture (MCE) was tested, in which the MCE was first sprayed on chicks in the hatchery followed by administration in the first drinking water. Three commercial flocks were treated and compared with parallel, untreated control flocks. Customary husbandry practices were employed. Environmental, hatchery, skin with feathers, and cecal samples were analyzed at 3 and 7 wk for the presence of salmonellae. Carcass rinse samples of fully processed birds were analyzed similarly. The results indicated that initial feed, water, and litter contamination was at a low frequency (10%). Eggshell fragments and chick paper pads were frequently contaminated (50%). After 3 wk growth, contamination of litter, skin with feathers, and ceca were significantly (P.05) reduced in treated flocks as compared with control flocks. Salmonellae prevalence in ceca and in processed carcass rinses was also significantly (P.05) reduced from 41% in control flocks to 10% in treated flocks. The study showed that treatment of chickens in a commercial setting with MCE cultures can serve as a useful means to reduce salmonellae contamination.