LEFKOVITCH'S ERROR

Abstract — Lefkovitch's formula for the probability of incompatibility between two binary characters can give incorrect results because it redundantly counts some possible compatibilities. The inaccuracy occurs when the characters have the same number of terminals showing the apomorphic state.     

Immunohistochemical distribution of S-100 protein and type IV collagen in human embryonic and fetal sympathetic neuroblasts

Summary The expression and distribution of S-100 protein and type IV collagen was studied immunohistochemically in sympathetic neuroblasts from the paravertebral region to the adrenal glands in human embryos and fetuses ranging from 7 to 12 weeks gestational age. Prom 7 weeks gestational age, S-100 protein was detected in round or oval cells mingling with sympathetic neuroblasts, and in spindle-shaped cells forming a continuous layer around them. The latter S-100 protein-positive cells were found in contact with the Schwann cells of nerve fibres entering the groups of sympathetic neuroblasts. Staining for type IV collagen showed that all groups of sympathetic neuroblasts were surrounded by a continuous basement membrane. By examining serial sections stained for type IV collagen and S-100 protein, a continuous basement membrane was found along the distribution pattern of the peripheral S-100 protein-positive spindle cells. The morphology of these cells, and their relationships with Schwann cells and with the basement membrane of the sympathetic neuroblasts, indicated that they were Schwann-like cells probably capable of synthesizing a continuous basement membrane separating the neuroblasts from the adjacent tissues. In contrast, the round or oval S-100 protein-positive cells, in contact with the sympathetic neuroblasts and not associated with nerve fibres, were considered as sustentacular or sustentacular precursor cells. At week 7 gestational age, the peri-adrenal sympathetic neuroblasts and their sustentacular and Schwann-like cells started to invade the adrenal glands and mingled with the adrenal cortical cells. These findings suggest the extra-adrenal origin of the sustentacular cells in embryonic and fetal adrenal glands.     

Malic acid production and consumption by selected of Saccharomyces cerevisiae under anaerobic and aerobic conditions

Summary Fermentation tests in clearly defined laboratory conditions were carried out with eight functionally selected strains of Saccharomyces cerevisiae. Analysis of the data showed that there were no significant differences in malic acid production between the strains when the acid was initially present. When it was initially absent, however, significant differences were observed two strains (Nos. 1141 and 1083) showing marked productive superiority. With malic acid as the sole C source, two strains (Nos. 1109 and 1141) showed less acid consumption.     

A Hamster-Derived West Nile Virus Isolate Induces Persistent Renal Infection in Mice

Background

West Nile virus (WNV) can persist long term in the brain and kidney tissues of humans, non-human primates, and hamsters. In this study, mice were infected with WNV strain H8912, previously cultured from the urine of a persistently infected hamster, to determine its pathogenesis in a murine host.

Methodology/Principal Findings

We found that WNV H8912 was highly attenuated for neuroinvasiveness in mice. Following a systemic infection, viral RNA could be detected quickly in blood and spleen and much later in kidneys. WNV H8912 induced constitutive IL-10 production, upregulation of IFN-β and IL-1β expression, and a specific IgM response on day 10 post-infection. WNV H8912 persisted preferentially in kidneys with mild renal inflammation, and less frequently in spleen for up to 2.5 months post infection. This was concurrent with detectable serum WNV-specific IgM and IgG production. There were also significantly fewer WNV- specific T cells and lower inflammatory responses in kidneys than in spleen. Previous studies have shown that systemic wild-type WNV NY99 infection induced virus persistence preferentially in spleen than in mouse kidneys. Here, we noted that splenocytes of WNV H8912-infected mice produced significantly less IL-10 than those of WNV NY99-infected mice. Finally, WNV H8912 was also attenuated in neurovirulence. Following intracranial inoculation, WNV persisted in the brain at a low frequency, concurrent with neither inflammatory responses nor neuronal damage in the brain.

Conclusions

WNV H8912 is highly attenuated in both neuroinvasiveness and neurovirulence in mice. It induces a low and delayed anti-viral response in mice and preferentially persists in the kidneys.     

Origins and Evolution of the Etruscans’ mtDNA

The Etruscan culture is documented in Etruria, Central Italy, from the 8^th to the 1^st century BC. For more than 2,000 years there has been disagreement on the Etruscans’ biological origins, whether local or in Anatolia. Genetic affinities with both Tuscan and Anatolian populations have been reported, but so far all attempts have failed to fit the Etruscans’ and modern populations in the same genealogy. We extracted and typed the hypervariable region of mitochondrial DNA of 14 individuals buried in two Etruscan necropoleis, analyzing them along with other Etruscan and Medieval samples, and 4,910 contemporary individuals from the Mediterranean basin. Comparing ancient (30 Etruscans, 27 Medieval individuals) and modern DNA sequences (370 Tuscans), with the results of millions of computer simulations, we show that the Etruscans can be considered ancestral, with a high degree of confidence, to the current inhabitants of Casentino and Volterra, but not to the general contemporary population of the former Etruscan homeland. By further considering two Anatolian samples (35 and 123 individuals) we could estimate that the genetic links between Tuscany and Anatolia date back to at least 5,000 years ago, strongly suggesting that the Etruscan culture developed locally, and not as an immediate consequence of immigration from the Eastern Mediterranean shores.     

Rapid identification of ubiquitination and SUMOylation target sites by microfluidic peptide array

SUMOylation and ubiquitination are two essential post translational modifications (PTMs) involved in the regulation of important biological processes in eukaryotic cells. Identification of ubiquitin (Ub) and small ubiquitin-related modifier (SUMO)-conjugated lysine residues in proteins is critical for understanding the role of ubiquitination and SUMOylation, but remains experimentally challenging. We have developed a powerful in vitro Ub/SUMO assay using a novel high density peptide array incorporated within a microfluidic device that allows rapid identification of ubiquitination and SUMOylation sites on target proteins. We performed the assay with a panel of human proteins and a microbial effector with known target sites for Ub or SUMO modifications, and determined that 80% of these proteins were modified by Ub or specific SUMO isoforms at the sites previously determined using conventional methods. Our results confirm the specificity for both SUMO isoform and individual target proteins at the peptide level. In summary, this microfluidic high density peptide array approach is a rapid screening assay to determine sites of Ub and SUMO modification of target substrates, which will provide new insights into the composition, selectivity and specificity of these PTM target sites.     

Estimating Encounter Rates and Densities of Three Lemur Species in Northeastern Madagascar

Primate populations, including Madagascar’s lemurs, are threatened worldwide and conservationists need accurate population estimates to develop targeted conservation plans. We sought to fill knowledge gaps for three lemur taxa —white-fronted brown lemur (Eulemur albifrons); eastern woolly lemur (Avahi laniger); and Allocebus/Microcebus, a category combining observations of hairy-eared dwarf lemurs (Allocebus trichotis) and mouse lemurs (Microcebus spp.)— in northeastern Madagascar by estimating their density, examining how their encounter rates and densities vary across three different forest types, and monitoring trends in encounter rates and densities at resurveyed sites, using data from surveys at six forest sites over a 4-year period (2010–2013). Landscape density for white-fronted brown lemur, eastern woolly lemur, and Allocebus/Microcebus was 21.5 (SE 3.67), 57.7 (SE 9.17), and 39.1 (SE 9.55) individuals/km², respectively. There was no difference in density estimates at intact and intermediately degraded forest sites; however, we encountered white-fronted brown lemurs more often in intact forest (1.64 ± SE 0.40 individuals/km) than in intermediately degraded and degraded forest (0.15 ± SE 0.06 and 0.16 ± SE 0.06 individuals/km). In addition, we encountered white-fronted brown lemurs at lower rates in 2013 (0.15 ± SE 0.06 individuals/km) compared to 2010 (0.82 ± SE 0.12 individuals/km) at a resurveyed site. Our findings emphasize that primate researchers must account for variation in how lemur encounter rates and densities differ between intact and degraded forests, and although we observed a decline in white-fronted brown lemur encounter rate at our resurveyed site, we caution that changes in lemur encounter rates may simply reflect lower detection rates rather than lower density. Future research should focus on using conventional distance sampling techniques, which are infrequently used in primate studies, to provide more robust density estimates as a way to accurately assess trends and the effects of anthropogenic pressures on lemur populations.     

Occupancy Modeling Reveals Interspecific Variation in Habitat Use and Negative Effects of Dogs on Lemur Populations

International Journal of Primatology - Effective, targeted management and conservation plans for wildlife populations require reliable population sampling and estimation. Unfortunately, robust,...     

Cognate T cell help is sufficient to trigger anti-nuclear autoantibodies in naive mice

The mechanisms involved in the initiation of anti-nuclear autoantibodies are unknown. In this study, we show that one factor allowing anti-nuclear autoantibodies to develop is the incomplete nature of immune tolerance to many of these proteins. Immune responses in mice toward the ubiquitous nuclear autoantigen La/SS-B are much weaker than responses to the xenoantigen, human La (hLa; 74% identical). However, in transgenic (Tg) mice expressing hLa, the Ab response to this neo-autoantigen was reduced to a level resembling the weak autoimmune response to mouse LA: Partial tolerance to endogenous La autoantigen was restricted to the T compartment because transfer of CD4(+) T cells specific for one or more hLa determinants into mice bearing the hLa transgene was sufficient to elicit production of anti-hLa autoantibodies. Notably, only hLa- specific T cells from non-Tg mice, and not T cells from hLa Tg mice, induced autoantibody production in hLa Tg mice. These findings confirm partial Th tolerance to endogenous La and indicate the existence in normal animals of autoreactive B cells continuously presenting La nuclear AG: Therefore, the B cell compartment is constitutively set to respond to particular nuclear autoantigens, implicating limiting Th responses as a critical checkpoint in the development of anti-nuclear autoantibodies in normal individuals.     

Kinetics of amyloid beta-protein degradation determined by novel fluorescence- and fluorescence polarization-based assays

Proteases that degrade the amyloid beta-protein (Abeta) are important regulators of brain Abeta levels in health and in Alzheimer's disease, yet few practical methods exist to study their detailed kinetics. Here, we describe robust and quantitative Abeta degradation assays based on the novel substrate, fluorescein-Abeta-(1-40)-Lys-biotin (FAbetaB). Liquid chromatography/mass spectrometric analysis shows that FAbetaB is hydrolyzed at closely similar sites as wild-type Abeta by neprilysin and insulin-degrading enzyme, the two most widely studied Abeta-degrading proteases. The derivatized peptide is an avid substrate and is suitable for use with biological samples and in high throughput compound screening. The assays we have developed are easily implemented and are particularly useful for the generation of quantitative kinetic data, as we demonstrate by determining the kinetic parameters of FAbetaB degradation by several Abeta-degrading proteases, including plasmin, which has not previously been characterized. The use of these assays should yield additional new insights into the biology of Abeta-degrading proteases and facilitate the identification of activators and inhibitors of such enzymes.