Modification of the protein glycosylation pathway in the methylotrophic yeast Pichia pastoris

-1,2-Mannosidase from Trichoderma reesei was used to modify the N-linked glycosylation pathway of the methylotrophic yeast Pichia pastoris. Expression of foreign influenza glycoproteins with more extensively processed N-linked oligosaccharides was observed when -1,2-mannosidase was secreted in the culture medium. However, intracellular removal of mannose residues may stimulate mannosyltransferase activity and leads to hyperglycosylation. [3H]Mannose suicide selection or high concentrations of orthovanadate, commonly used to isolate glycosylation mutants of Saccharomyces cerevisiae, had no profound effect on Pichia pastoris. © Rapid Science Ltd. 1998     

Medically Complex Pregnancies and Early Breastfeeding Behaviors: A Retrospective Analysis

Background

Breastfeeding is beneficial for women and infants, and medical contraindications are rare. Prenatal and labor-related complications may hinder breastfeeding, but supportive hospital practices may encourage women who intend to breastfeed. We measured the relationship between having a complex pregnancy (entering pregnancy with hypertension, diabetes, or obesity) and early infant feeding, accounting for breastfeeding intentions and supportive hospital practices.

Methods

We performed a retrospective analysis of data from a nationally-representative survey of women who gave birth in 2011–2012 in a US hospital (N = 2400). We used logistic regression to examine the relationship between pregnancy complexity and breastfeeding. Self-reported prepregnancy diabetes or hypertension, gestational diabetes, or obesity indicated a complex pregnancy. The outcome was feeding status 1 week postpartum; any breastfeeding was evaluated among women intending to breastfeed (N = 1990), and exclusive breastfeeding among women who intended to exclusively breastfeed (N = 1418). We also tested whether breastfeeding intentions or supportive hospital practices mediated the relationship between pregnancy complexity and infant feeding status.

Results

More than 33% of women had a complex pregnancy; these women had 30% lower odds of intending to breastfeed (AOR = 0.71; 95% CI, 0.52–0.98). Rates of intention to exclusively breastfeed were similar for women with and without complex pregnancies. Women who intended to breastfeed had similar rates of any breastfeeding 1 week postpartum regardless of pregnancy complexity, but complexity was associated with >30% lower odds of exclusive breastfeeding 1 week among women who intended to exclusively breastfeed (AOR = 0.68; 95% CI, 0.47–0.98). Supportive hospital practices were strongly associated with higher odds of any or exclusive breastfeeding 1 week postpartum (AOR = 4.03; 95% CI, 1.81–8.94; and AOR = 2.68; 95% CI, 1.70–4.23, respectively).

Conclusions

Improving clinical and hospital support for women with complex pregnancies may increase breastfeeding rates and the benefits of breastfeeding for women and infants.     

Mitochondrial free Ca2+ concentration in living cells

Evidence has accrued during the past two decades that mitochondrial Ca²⁺ plays an important role in the regulation of numerous cell functions such as energy metabolism. This implies that mitochondrial Ca²⁺ transport systems might be able to relay the changes of cytosolic Ca²⁺ concentration ([Ca²⁺]_c) into mitochondrial matrix for regulating biochemical activities. To substantiate this idea, measurements of intramitochondrial free Ca²⁺ concentration ([Ca²⁺]_m) become essential. In this article, we review the results from recent studies attempting to measure [Ca²⁺]_m in living cells. In addition, the significance of each study is discussed.     

UMARS: Un-MAppable Reads Solution

Background

Few high-resolution structures of integral membranes proteins are available, as crystallization of such proteins needs yet to overcome too many technical limitations. Nevertheless, prediction of their transmembrane (TM) structure by bioinformatics tools provides interesting insights on the topology of these proteins.

Methods

We describe here how to extract new information from the analysis of hydrophobicity variations or hydrophobic pulses (HPulses) in the sequence of integral membrane proteins using the Hydrophobic Pulse Predictor, a new tool we developed for this purpose. To analyze the primary sequence of 70 integral membrane proteins we defined two levels of analysis: G1-HPulses for sliding windows of n = 2 to 6 and G2-HPulses for sliding windows of n = 12 to 16.

Results

The G2-HPulse analysis of 541 transmembrane helices allowed the definition of the new concept of transmembrane unit (TMU) that groups together transmembrane helices and segments with potential adjacent structures. In addition, the G1-HPulse analysis identified helix irregularities that corresponded to kinks, partial helices or unannotated structural events. These irregularities could represent key dynamic elements that are alternatively activated depending on the channel status as illustrated by the crystal structures of the lactose permease in different conformations.

Conclusions

Our results open a new way in the understanding of transmembrane secondary structures: hydrophobicity through hydrophobic pulses strongly impacts on such embedded structures and is not confined to define the transmembrane status of amino acids.     

LPA1/3 signaling mediates tumor lymphangiogenesis through promoting CRT expression in prostate cancer

Lysophosphatidic acid (LPA) is a bioactive lipid growth factor which is present in high levels in serum and platelets. LPA binds to its specific G-protein-coupled receptors, including LPA₁ to LPA₆, thereby regulating various physiological functions, including cancer growth, angiogenesis, and lymphangiogenesis. Our previous study showed that LPA promotes the expression of the lymphangiogenic factor vascular endothelial growth factor (VEGF)-C in prostate cancer (PCa) cells. Interestingly, LPA has been shown to regulate the expression of calreticulin (CRT), a multifunctional chaperone protein, but the roles of CRT in PCa progression remain unclear. Here we investigated the involvement of CRT in LPA-mediated VEGF-C expression and lymphangiogenesis in PCa. Knockdown of CRT significantly reduced LPA-induced VEGF-C expression in PC-3 cells. Moreover, LPA promoted CRT expression through LPA receptors LPA₁ and LPA₃, reactive oxygen species (ROS) production, and phosphorylation of eukaryotic translation initiation factor 2α (eIF2α). Tumor-xenografted mouse experiments further showed that CRT knockdown suppressed tumor growth and lymphangiogenesis. Notably, clinical evidence indicated that the LPA-producing enzyme autotaxin (ATX) is related to CRT and that CRT level is highly associated with lymphatic vessel density and VEGF-C expression. Interestingly, the pharmacological antagonist of LPA receptors significantly reduced the lymphatic vessel density in tumor and lymph node metastasis in tumor-bearing nude mice. Together, our results demonstrated that CRT is critical in PCa progression through the mediation of LPA-induced VEGF-C expression, implying that targeting the LPA signaling axis is a potential therapeutic strategy for PCa.     

Double balanced de novo translocations involving chromosomes 4/15 and 5/12 in a mentally retarded boy

This report describes a compound structural rearrangement containing two apparently unrelated reciprocal translocations, one between chromosomes 4 and 15, the other between 5 and 12. It is suggested that the patient's mental retardation and osteosclerosis may be the result of the loss of a small amount of chromosomal material and/or position effect accompanying these translocations.     

Infantile parkinsonism and gabaergic hypotransmission in a patient with pyruvate carboxylase deficiency

Pyruvate carboxylase deficiency is a rare metabolic disorder, with three different phenotypes. We aim to report the case of a newborn presenting the severe neonatal form of this deficiency (the B or “French” phenotype, hypokinesia and rigidity being the main features) and the results of the study of classic neurotransmitters involved in movement control. Hyperdopaminergic transmission (both in the cerebrospinal fluid and in the substantia nigra) and hypoGABAergic transmission (in the substantia nigra) were found. Both gamma-aminobutyric acid and dopamine markers were found coexisting in individual neurons of the substantia nigra. This is the first time this phenomenon has been reported in the literature. We discuss the possible role of GABAergic deficiency, its interaction with other neurotransmitters and its implication in neurotransmitter homeostasis. A better comprehension of that field would increase understanding of the pathophysiology of neurological symptoms and neurotransmitter plasticity.