Chromatid recommensuration after segmental duplication

<p>Abstract</p> <p>Background</p> <p>Midsegment duplication (dup) of chromatid arms may be symmetric or asymmetric. It can be argued that every dup should yield a discommensured RC with (a) loss of at least one duplicated unit to the template counterpart and; (b) deletion of all sections of the replicating chromatid arm that are distal to both the gap left by the duplicating process and the segment closest to the centromere.</p> <p>Hypothesis</p> <p>Mechanisms capable of recommensuring the stack of chromatids after topological shifts of duplicated units (dups) are discussed. The mechanics might fail in few cases, which are discussed in terms of statistics and scalability.</p> <p>Conclusion</p> <p>The dynamics of the highly non-linear processes discussed here may be relevant to duplications of smaller (epsilon) subunits such as telomeric units within malignant genomes.</p

Gonadal Transcriptome Alterations in Response to Dietary Energy Intake: Sensing the Reproductive Environment

Reproductive capacity and nutritional input are tightly linked and animals' specific responses to alterations in their physical environment and food availability are crucial to ensuring sustainability of that species. We have assessed how alterations in dietary energy intake (both reductions and excess), as well as in food availability, via intermittent fasting (IF), affect the gonadal transcriptome of both male and female rats. Starting at four months of age, male and female rats were subjected to a 20% or 40% caloric restriction (CR) dietary regime, every other day feeding (IF) or a high fat-high glucose (HFG) diet for six months. The transcriptional activity of the gonadal response to these variations in dietary energy intake was assessed at the individual gene level as well as at the parametric functional level. At the individual gene level, the females showed a higher degree of coherency in gonadal gene alterations to CR than the males. The gonadal transcriptional and hormonal response to IF was also significantly different between the male and female rats. The number of genes significantly regulated by IF in male animals was almost 5 times greater than in the females. These IF males also showed the highest testosterone to estrogen ratio in their plasma. Our data show that at the level of gonadal gene responses, the male rats on the IF regime adapt to their environment in a manner that is expected to increase the probability of eventual fertilization of females that the males predict are likely to be sub-fertile due to their perception of a food deficient environment

Phosphorus Supplementation Mitigated Food Intake and Growth of Rats Fed a Low-Protein Diet

BACKGROUND: Low protein intake is associated with various negative health outcomes at any life stage. When diets do not contain sufficient protein, phosphorus availability is compromised because proteins are the major sources of phosphorus. However, whether mineral phosphorus supplementation mitigates this problem is unknown, to our knowledge. OBJECTIVE: Our goal was to determine the impact of dietary phosphorus supplementation on food intake, weight gain, energy efficiency, body composition, blood metabolites, and liver histology in rats fed a low-protein diet for 9 wk. METHODS: Forty-nine 6-wk-old male Sprague-Dawley rats were randomly allocated to 5 groups and consumed 5 isocaloric diets ad libitum that varied only in protein (egg white) and phosphorus concentrations for 9 wk. The control group received a 20% protein diet with 0.3% P (NP-0.3P). The 4 other groups were fed a low-protein (10%) diet with a phosphorus concentration of 0.015%, 0.056%, 0.1%, or 0.3% (LP-0.3P). The rats' weight, body and liver composition, and plasma biomarkers were then assessed. RESULTS: The addition of phosphorus to the low-protein diet significantly increased food intake, weight gain, and energy efficiency, which were similar among the groups that received 0.3% P (LP-0.3P and NP-0.3P) regardless of dietary protein content. In addition, phosphorus supplementation of low-protein diets reduced plasma urea nitrogen and increased total body protein content (defatted). Changes in food intake and efficiency, body weight and composition, and plasma urea concentration were highly pronounced at a dietary phosphorus content &lt;0.1%, which may represent a critical threshold. CONCLUSIONS: The addition of phosphorus to low-protein diets improved growth measures in rats, mainly as a result of enhanced energy efficiency. A dietary phosphorus concentration of 0.3% mitigated detrimental effects of low-protein diets on growth parameters

Aberrant Angiogenic Characteristics of Human Brain Arteriovenous Malformation Endothelial Cells

Objective: To identify and characterize the phenotypic and functional differences of endothelial cells derived from cerebral arteriovenous malformations (AVM), as compared with endothelial cells derived from a normal brain. Methods: Isolated AVM brain endothelial cells and control brain endothelial cells were evaluated immunohistochemically for expression of the endothelial cell markers von Willebrand factor and CD31, as well as angiogenic factors including vascular endothelial growth factor A, interleukin-8, and endothelin-1. Vascular endothelial growth factor receptors 1 and 2 were also evaluated using immunohistochemistry techniques. Functional assays evaluated cell proliferation, cytokine production, tubule formation, and cell migration using the modified Boyden chamber technique. Results: Endothelial cells derived from AVMs expressed high levels of vascular endothelial growth factor A and significantly overexpressed the vascular endothelial growth factor receptors 1 and 2 (P < 0.05), as compared with control endothelial cells. In addition, comparison to control brain endothelial cells demonstrated that AVM brain endothelial cells proliferated faster, migrated more quickly, and produced aberrant tubule-like structures. Conclusion: Endothelial cells derived from cerebral AVMs are highly activated cells overexpressing proangiogenic growth factors and exhibiting abnormal functions consistent with highly activated endothelial cells

Targeting acute myeloid leukemia by dual inhibition of PI3K signaling and Cdk9-mediated Mcl-1 transcription

Resistance to cell death is a hallmark of cancer and renders transformed cells resistant to multiple apoptotic triggers. The Bcl-2 family member, Mcl-1, is a key driver of cell survival in diverse cancers, including acute myeloid leukemia (AML). A screen for compounds that downregulate Mcl-1 identified the kinase inhibitor, PIK-75, which demonstrates marked proapoptotic activity against a panel of cytogenetically diverse primary human AML patient samples. We show that PIK-75 transiently blocks Cdk7/9, leading to transcriptional suppression of MCL-1, rapid loss of Mcl-1 protein, and alleviation of its inhibition of proapoptotic Bak. PIK-75 also targets the p110&alpha; isoform of PI3K, which leads to a loss of association between Bcl-xL and Bak. The simultaneous loss of Mcl-1 and Bcl-xL association with Bak leads to rapid apoptosis of AML cells. Concordantly, low Bak expression in AML confers resistance to PIK-75&ndash;mediated killing. On the other hand, the induction of apoptosis by PIK-75 did not require the expression of the BH3 proteins Bim, Bid, Bad, Noxa, or Puma. PIK-75 significantly reduced leukemia burden and increased the survival of mice engrafted with human AML without inducing overt toxicity. Future efforts to cotarget PI3K and Cdk9 with drugs such as PIK-75 in AML are warranted