Cytomegalovirus seropositivity is associated with glucose regulation in the oldest old. Results from the Leiden 85-plus Study

ABSTRACT: BACKGROUND: Cytomegalovirus (CMV) infection has been reported to contribute to the pathogenesis of type 1 diabetes and post-transplantation diabetes. However, CMV infection has not been evaluated as a possible risk factor for type 2 diabetes. Our aim was to investigate potential associations between CMV seropositivity, CMV IgG antibody level and glucose regulation in the oldest old. RESULTS: CMV seropositive subjects were more likely to have type 2 diabetes (17.2% vs 7.9%, p = 0.016), had a higher level of HbA1c (p = 0.014) and higher non-fasting glucose (p = 0.024) in the oldest olds. These associations remained significant after adjustment for possible confounders. CMV IgG antibody level was not significantly associated with glucose regulation (all p > 0.05). CONCLUSIONS: In the oldest old, CMV seropositivity is significantly associated with various indicators of glucose regulation. This finding suggests that CMV infection might be a risk factor for the development of type 2 diabetes in the elderly.     

Caecal size and function in the rock elephant shrew Elephantulus myurus (Insectivora, Macroscelididae) and the Namaqua rock mouse Aethomys namaquensis (Rodentia, Muridae)

1. The relative size of the digestive organs and the function of the caeca of an insectivorous elephant shrew Elephantulus myurus (Macroscelididae) and of a herbivorous rodent Aethomys namaquensis (Muridae) were compared. 2. Both species had similar body mass but A. namaquensis had a significantly heavier total digestive tract, full stomach, and caecum and a longer large intestine and caecum than E. myurus. 3. Both species had similar total volatile fatty acid (VFA) concentration and VFA % composition although A. namaquensis had a significantly higher % of n-butyric acid. Both had a similar caecal NH3-N concentration. 4. The presence of a functional caecum in E. myurus supports the view that Macroscelididae have evolved from ancestral herbivores and not from insectivores.     

An improved technique for obtaining well-spread metaphases from plants with numerous large chromosomes

Preparations that contain well-spread metaphase chromosomes are critical for plant cytogenetic analyses including chromosome counts, banding procedures, in situ hybridization, karyotyping and construction of ideograms. Chromosome spreading is difficult for plants with large and numerous chromosomes. We report here a technique for obtaining cytoplasm-free, well-spread metaphases from two Amaryllidaceae species: Sprekelia formosissima (2n = 120) and Hymenocallis howardii (2n = 96). The technique has three main steps: 1) pretreatment to cause chromosome condensation, 2) dripping onto tilted slides coated with a thin layer of pure acetic acid and 3) application of steam and acetic acid to produce cytoplasmic hydrolysis, which spreads the chromosomes.     

Unconventional signalling in tunicates

The zooids in colonial tunicates do not appear to be directly interconnected by nerves, but this has not prevented the evolution of coordinated behaviour in several groups. In Botryllus and other colonial styelid asci‐dians the endothelium lining the blood vessels is excitable and transmits action potentials from cell to cell via gap junctions. These signals mediate protective contractions of the zooids and synchronize contractions of the vascular ampullae. In didemnid ascidians such as Diplosoma a network of myocytes in the tunic serves to transmit excitation and to cause contractions of the cloacal apertures. Individual zooids of Pyrosoma protect themselves by closing their siphons and arresting their branchial cilia when stimulated. At the same time a flash of light is emitted. Neighbouring zooids sense the flash with their photoreceptors and respond in turn with protective responses and light emission. Protective responses thus spread by photic signalling and propagate from zooid to zooid through the colony in a saltatory manner. In chains of Salpafusifortnis, changes in the direction and/or speed of swimming are transmitted from zooid to zooid via adhesion plaques. When a zooid is stimulated, its body‐wall epithelium conducts action potentials to the plaque connecting it to the next zooid, exciting receptor neurons in that zooid. These receptors have sensory processes that bridge the gap between the two zooids. The sensory neurons so excited in the second zooid conduct impulses to the brain where they alter the motor output pattern, and at the same time generate epithelial action potentials that travel to the next zooid in line, where the same thing happens.

It is not clear why these unconventional signalling methods have evolved but the tunic may be an inhospitable environment for nerves, making conventional nervous links impossible.     

Effect of weight loss and exercise on angiogenic factors in the circulation and in adipose tissue in obese subjects

Background:

Vascular growth is a prerequisite for adipose tissue (AT) development and expansion. Some AT cytokines and hormones have effects on vascular development, like vascular endothelial growth factor (VEGF‐A), angiopoietin (ANG‐1), ANG‐2 and angiopoietin‐like protein‐4 (ANGPTL‐4).

Methods:

In this study, the independent and combined effects of diet‐induced weight loss and exercise on AT gene expression and proteins levels of those angiogenic factors were investigated. Seventy‐nine obese males and females were randomized to: 1. Exercise‐only (EXO; 12‐weeks exercise without diet‐restriction), 2. Hypocaloric diet (DIO; 8‐weeks very low energy diet (VLED) + 4‐weeks weight maintenance diet) and 3. Hypocaloric diet and exercise (DEX; 8‐weeks VLED + 4‐weeks weight maintenance diet combined with exercise throughout the 12 weeks). Blood samples and fat biopsies were taken before and after the intervention.

Results:

Weight loss was 3.5 kg in the EXO group and 12.3 kg in the DIO and DEX groups. VEGF‐A protein was non‐significantly reduced in the weight loss groups. ANG‐1 protein levels were significantly reduced 22‐25% after all three interventions (P < 0.01). The ANG‐1/ANG‐2 ratio was also decreased in all three groups (P < 0.05) by 27‐38%. ANGPTL‐4 was increased in the EXO group (15%, P < 0.05) and 9% (P < 0.05) in the DIO group. VEGF‐A, ANG‐1, and ANGPTL‐4 were all expressed in human AT, but only ANGPTL‐4 was influenced by the interventions.

Conclusions:

Our data show that serum VEGF‐A, ANG‐1, ANG‐2, and ANGPTL‐4 levels are influenced by weight changes, indicating the involvement of these factors in the obese state. Moreover, it was found that weight loss generally was associated with a reduced angiogenic activity in the circulation.     

Lactate dehydrogenase (LDH) gene duplication during chordate evolution: the cDNA sequence of the LDH of the tunicate Styela plicata

L-Lactate dehydrogenase (L-LDH, E.C. 1.1.1.27) is encoded by two or three loci in all vertebrates examined, with the exception of lampreys, which have a single LDH locus. Biochemical characterizations of LDH proteins have suggested that a gene duplication early in vertebrate evolution gave rise to Ldh-A and Ldh-B and that an additional locus, Ldh-C arose in a number of lineages more recently. Although some phylogenetic studies of LDH protein sequences have supported this pattern of gene duplication, others have contradicted it. In particular, a number of studies have suggested that Ldh-C represents the earliest divergence among vertebrate LDHs and that it may have diverged from the other loci well before the origin of vertebrates. Such hypotheses make explicit statements about the relationship of vertebrate and invertebrate LDHs, but to date, no closely related invertebrate LDH sequences have been available for comparison. We have attempted to provide further data on the timing of gene duplications leading to multiple vertebrate LDHs by determining the cDNA sequence of the LDH of the tunicate Styela plicata. Phylogenetic analyses of this and other LDH sequences provide strong support for the duplications giving rise to multiple vertebrate LDHs having occurred after vertebrates diverged from tunicates. The timing of these LDH duplications is consistent with data from a number of other gene families suggesting widespread gene duplication near the origin of vertebrates. With respect to the relationships among vertebrate LDHs, our data are not consistent with previous claims that Ldh-C represented the earliest divergence. However, the precise relationships among some of the main lineages of vertebrate LDHs were not resolved in our analyses.      

Atomistic details of effect of disulfide bond reduction on active site of Phytase B from Aspergillus niger: A MD Study

The molecular integrity of the active site of phytases from fungi is critical for maintaining phytase function as efficient catalytic machines. In this study, the molecular dynamics (MD) of two monomers of phytase B from Aspergillus niger, the disulfide intact monomer (NAP) and a monomer with broken disulfide bonds (RAP), were simulated to explore the conformational basis of the loss of catalytic activity when disulfide bonds are broken. The simulations indicated that the overall secondary and tertiary structures of the two monomers were nearly identical but differed in some crucial secondary–structural elements in the vicinity of the disulfide bonds and catalytic site. Disulfide bonds stabilize the β-sheet that contains residue Arg66 of the active site and destabilize the α-helix that contains the catalytic residue Asp319. This stabilization and destabilization lead to changes in the shape of the active–site pocket. Functionally important hydrogen bonds and atomic fluctuations in the catalytic pocket change during the RAP simulation. None of the disulfide bonds are in or near the catalytic pocket but are most likely essential for maintaining the native conformation of the catalytic site.

Abbreviations

PhyB - 2.5 pH acid phophatese from Aspergillus niger, NAP - disulphide intact monomer of Phytase B, RAP - disulphide reduced monomer of Phytase B, Rg - radius of gyration, RMSD - root mean square deviation, MD - molecular dynamics.     

Altering the Divalent Metal Ion Preference of RNase E

RNase E is a major intracellular endoribonuclease in many bacteria and participates in most aspects of RNA processing and degradation. RNase E requires a divalent metal ion for its activity. We show that only Mg²⁺ and Mn²⁺ will support significant rates of activity in vitro against natural RNAs, with Mn²⁺ being preferred. Both Mg²⁺ and Mn²⁺ also support cleavage of an oligonucleotide substrate with similar kinetic parameters for both ions. Salts of Ni²⁺ and Zn²⁺ permitted low levels of activity, while Ca²⁺, Co³⁺, Cu²⁺, and Fe²⁺ did not. A mutation to one of the residues known to chelate Mg²⁺, D346C, led to almost complete loss of activity dependent on Mg²⁺; however, the activity of the mutant enzyme was fully restored by the presence of Mn²⁺ with kinetic parameters fully equivalent to those of wild-type enzyme. A similar mutation to the other chelating residue, D303C, resulted in nearly full loss of activity regardless of metal ion. The properties of RNase E D346C enabled a test of the ionic requirements of RNase E in vivo. Plasmid shuffling experiments showed that both rneD303C (i.e., the rne gene encoding a D-to-C change at position 303) and rneD346C were inviable whether or not the selection medium was supplied with MnSO₄, implying that RNase E relies on Mg²⁺ exclusively in vivo.