Genomic and Epigenetic Foundations of Neocentromere Formation.

Centromeres are essential to genome inheritance, serving as the site of kinetochore assembly and coordinating chromosome segregation during cell division. Abnormal centromere function is associated with birth defects, infertility, and cancer. Normally, centromeres are assembled and maintained at the same chromosomal location. However, ectopic centromeres form spontaneously at new genomic locations and contribute to genome instability and developmental defects as well as to acquired and congenital human disease. Studies in model organisms have suggested that certain regions of the genome, including pericentromeres, heterochromatin, and regions of open chromatin or active transcription, support neocentromere activation. However, there is no universal mechanism that explains neocentromere formation. This review focuses on recent technological and intellectual advances in neocentromere research and proposes future areas of study. Understanding neocentromere biology will provide a better perspective on chromosome and genome organization and functional context for information generated from the Human Genome Project, ENCODE, and other large genomics consortia.

Frozen Mother's Own Milk Can Be Used Effectively to Personalize Donor Human Milk.

Feeding preterm infants mother's own milk (MOM) lowers rates of sepsis, decreases necrotizing enterocolitis, and shortens hospital stay. In the absence of freshly expressed MOM, frozen MOM (FMOM) is provided. When MOM is unavailable, preterm infants are often fed pasteurized donor human milk (DHM), rendering it devoid of beneficial bacteria. We have previously reported that when MOM is inoculated into DHM to restore the live microbiota [restored milk (RM)], a similar microbial diversity to MOM can be achieved. Yet, it is unknown if a similar diversity to MOM can be obtained when FMOM is inoculated into DHM. The goal of this study was to determine whether a similar microbial composition to MOM could be obtained when FMOM is used to personalize DHM. To this end, a fresh sample of MOM was obtained and divided into fresh and frozen fractions. MOM and FMOM were inoculated into DHM at different dilutions: MOM/FMOM 10% (RM/FRM10) and MOM/FMOM 30% (RM/FRM30) and incubated at 37°C. At different timepoints, culture-dependent and culture-independent techniques were performed. Similar microbiota expansion and alpha diversity were observed in MOM, RM10, and RM30 whether fresh or frozen milk was used as the inoculum. To evaluate if microbial expansion would result in an abnormal activation on the innate immune system, Caco-2 epithelial cells were exposed to RM/FRM to compare interleukin 8 levels with Caco-2 cells exposed to MOM or DHM. It was found that RM samples did not elicit a significant increase in IL-8 levels when compared to MOM or FMOM. These results suggest that FMOM can be used to inoculate DHM if fresh MOM is unavailable or limited in supply, allowing both fresh MOM and FMOM to be viable options in a microbial restoration strategy.

Sex Modulates Lactobacillus johnsonii N6.2 and Phytophenol Effectiveness in Reducing High Fat Diet Induced mTOR Activation in Sprague-Dawley Rats.

Metabolic syndrome (MetS) is the underlying cause of some devastating diseases, including type 2 diabetes and cardiovascular disease. These diseases have been associated with over-activation of the mechanistic Target of Rapamycin (mTOR) pathway. This study utilizes a high fat diet (HFD) to induce MetS and to dissect the effects of a beneficial bacterium, L. johnsonii N6.2, and natural phenolics on mTOR complex 1 (mTORC1) expression compared to a reduced energy density diet (REDD). HFD significantly elevated MetS markers in males, as noted through an increase in weight, glucose levels, and triglyceride levels. Treatments were effective in reducing mTORC1-activating phosphorylation of pAKT-T308 and pAKT-S473 (p = 0.0012 and 0.0049, respectively) in HFD-fed females, with the combined treatments of L. johnsonii and phytophenols reducing phosphorylation below REDD-fed control levels, and significantly below HFD-fed control levels. Meanwhile, diet was the significant factor influencing male mTORC1-activating phosphorylation (p < 0.0001), as treatments were only effective in reducing phosphorylation in REDD-fed animals. Downstream analysis of mTORC1 activated genes phosphogluconate dehydrogenase (pgd) and phosphofructose kinase (pfk) followed this similar trend, enforcing the significant effect sex has on a treatments' ability to modulate diet induced abnormalities. Analyzing mTORC1 stimulators such as insulin, inflammatory cytokines, and tryptophan, revealed no significant differences among groups. These results indicate that the effects observed on mTORC1 are a direct consequence of the treatments, and not exerted indirectly via the modulation of stimuli. This study highlights the potential use of commensal microorganisms and natural compounds in reducing the onset of metabolic diseases through mTORC1.