Benefiting friends or dominants: prosocial choices mainly depend on rank position in long-tailed macaques (<Emphasis Type="Italic">Macaca fascicularis</Emphasis>)

Long-term observational studies in a number of animal species suggest that exchange patterns of social acts depend on long-term emotional bonds. Therefore, it is expected that the frequency of prosocial behavior will depend on the strength of such a bond. In this study we tested whether variation in relationship quality among unrelated individuals, i.e., “friends” and “nonfriends,” is predictive of the prosocial behavior of long-tailed macaques in two experiments. First, we related relationship quality to prosociality in a dyadic prosociality test, and second, we gave subjects the choice to give to either a friend or a nonfriend in a triadic choice test. We show that prosocial behavior of long-tailed macaques in the dyadic test is not related to relationship quality. When given the choice to give to either a friend or a nonfriend in the triadic test, there is a minor indication that long-tailed macaques show a preference to give to their friends, yet this indication is neither significant nor consistent. In contrast, subordinate long-tailed macaques make a more “competitive” choice and avoid giving to the individual closest in rank. Therefore, in the short-term situation of experimental tests, prosocial behavior of long-tailed macaques seems unaffected by the relationship quality of the dyad/triad tested, and the relative dominance position of these dyads/triads seems to have a much stronger effect on their prosocial behavior.     

Clade 8 and Clade 6 Strains of Escherichia coli O157:H7 from Cattle in Argentina have Hypervirulent-Like Phenotypes

The hemolytic uremic syndrome (HUS) whose main causative agent is enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a disease that mainly affects children under 5 years of age. Argentina is the country with the highest incidence of HUS in the world. Cattle are a major reservoir and source of infection with E. coli O157:H7. To date, the epidemiological factors that contribute to its prevalence are poorly understood. Single nucleotide polymorphism (SNP) typing has helped to define nine E. coli O157:H7 clades and the clade 8 strains were associated with most of the cases of severe disease. In this study, eight randomly selected isolates of EHEC O157:H7 from cattle in Argentina were studied as well as two human isolates. Four of them were classified as clade 8 through the screening for 23 SNPs; the two human isolates grouped in this clade as well, while two strains were closely related to strains representing clade 6. To assess the pathogenicity of these strains, we assayed correlates of virulence. Shiga toxin production was determined by an ELISA kit. Four strains were high producers and one of these strains that belonged to a novel genotype showed high verocytotoxic activity in cultured cells. Also, these clade 8 and 6 strains showed high RBC lysis and adherence to epithelial cells. One of the clade 6 strains showed stronger inhibition of normal water absorption than E. coli O157:H7 EDL933 in human colonic explants. In addition, two of the strains showing high levels of Stx2 production and RBC lysis activity were associated with lethality and uremia in a mouse model. Consequently, circulation of such strains in cattle may partially contribute to the high incidence of HUS in Argentina.     

Breeding system of diploid sexuals within the Ranunculus auricomus complex and its role in a geographical parthenogenesis scenario

The larger distribution area of asexuals compared with their sexual relatives in geographical parthenogenesis (GP) scenarios has been widely attributed to the advantages of uniparental reproduction and polyploidy. However, potential disadvantages of sexuals due to their breeding system have received little attention so far. Here, we study the breeding system of five narrowly distributed sexual lineages of Ranunculus notabilis s.l. (R. auricomus complex) and its effects on outcrossing, inbreeding, female fitness, and heterozygosity. We performed selfing and intra‐ and interlineage crossings by bagging 481 flowers (59 garden individuals) followed by germination experiments. We compared seed set and germination rates, and related them to genetic distance and genome‐wide heterozygosity (thousands of RADseq loci). Selfings (2.5%) unveiled a significantly lower seed set compared with intra‐ (69.0%) and interlineage crossings (69.5%). Seed set of intra‐ (65%) compared to interpopulation crossings (78%) was significantly lower. In contrast, all treatments showed comparable germination rates (32%–43%). Generalized linear regressions between seed set and genetic distance revealed positive relationships in general and between lineages, and a negative one within lineages. Seed set was the main decisive factor for female fitness. Germination rates were not related to genetic distance at any level, but were positively associated with heterozygosity in interlineage crossings. Experiments confirmed full crossability and predominant outcrossing among sexual R. notabilis s.l. lineages. However, up to 5% (outliers 15%–31%) of seeds were formed by selfing, probably due to semi‐self‐compatibility in a multi‐locus gametophytic SI system. Less seed set in intrapopulation crossings, and higher seed set and germination rates from crossings of genetically more distant and heterozygous lineages (interlineage) indicate negative inbreeding and positive outbreeding effects. In GP scenarios, sexual species with small and/or isolated populations can suffer from decreased female fitness due to their breeding system. This factor, among others, probably limits range expansion of sexuals.     

Continuous acetone-butanol production with direct product removal

Summary To eliminate the product inhibition and increase the productivity of butanol formation, a continuously operated membrane bioreactor was connected to a four-stage mixer-settler cascade. Clostridium acetobutylicum was cultivated in this reactor. Butanol was selectively extracted with butyric acid saturated n-decanol from the cell-free cultivation medium, and the butanol-free medium was refed into the reactor. Due to the high boiling point of decanol, the recovery of butanol from the decanol solution is easy. The partition coefficient and selectivity of butanol in the cultivation medium-decanol-system is sufficiently high for removing it from the medium. Direct contact of the cells with the decanol phase causes cell damage. However, decanol is practically insoluble in the fermentation medium, thus the contact of the cell-free medium with the solvent phase does not influence of cell growth and product formation. At a dilution rate of D _z=0.1 h^-1, the butanol productivity was increased by removing butanol from the medium by a factor of four. A further increase was prevented by a contaminant of the technical decanol, which was identified by GC-MS-analysis as 1-,3-hexandiol.Symbols D dilution rate, h^-1 - D _eff effective dilution rate (Eq. 3), h^-1 - D _Ex extraction dilution rate (Eq. 3), h^-1 - D _g dilution rate of cell suspension in reactor-filter-system, h^-1 - E degree of extraction (Eq. 3), l - P product concentration in medium after extraction, g l^-1 - P _O product concentration in reactor, g l^-1 - R _P productivity and product formation rate, g l^-1 h^-1 - q _p S specific product formation coefficient with regard to the cell growth rate, l - V _F volume of cell suspension in filter module, l - V _g volume of the cell suspension in reactor and in filter module V _g =V _R +V _F , l - V _R volume of cell suspension in ractor, l - v _O cell free feed rate, l h^-1 - v ₁ flow rate of cell suspension leaves the reactor, l h^-1 - v _E flow rate of decanol through the extractor, l h^-1 - v _w flow rate of the cell free medium through the filter modul, l h^-1 - X cell mass concentration, g l^-1 - specific growth rate of the cells, h^-1 Dedicated to Professor Dr. H. J. Rehm on the occasion of his 60th birthday     

Laminin alpha5 is necessary for submandibular gland epithelial morphogenesis and influences FGFR expression through beta1 integrin signaling

Laminin alpha chains have unique spatiotemporal expression patterns during development and defining their function is necessary to understand the regulation of epithelial morphogenesis. We investigated the function of laminin alpha5 in mouse submandibular glands (SMGs). Lama5(-/-) SMGs have a striking phenotype: epithelial clefting is delayed, although proliferation occurs; there is decreased FGFR1b and FGFR2b, but no difference in Lama1 expression; later in development, epithelial cell organization and lumen formation are disrupted. In wild-type SMGs alpha5 and alpha1 are present in epithelial clefts but as branching begins alpha5 expression increases while alpha1 decreases. Lama5 siRNA decreased branching, p42 MAPK phosphorylation, and FGFR expression, and branching was rescued by FGF10. FGFR siRNA decreased Lama5 suggesting that FGFR signaling provides positive feedback for Lama5 expression. Anti-beta1 integrin antibodies decreased FGFR and Lama5 expression, suggesting that beta1 integrin signaling provides positive feedback for Lama5 and FGFR expression. Interestingly, the Itga3(-/-):Itga6(-/-) SMGs have a similar phenotype to Lama5(-/-). Our findings suggest that laminin alpha5 controls SMG epithelial morphogenesis through beta1 integrin signaling by regulating FGFR expression, which also reciprocally regulates the expression of Lama5. These data link changes in basement membrane composition during branching morphogenesis with FGFR expression and signaling.     

Evaluating Human Risk from Exposure to Alkylated PAHs in an Aquatic System

Polycyclic aromatic hydrocarbons (PAHs) are a large class of organic chemicals typically found as mixtures in the aquatic environment from natural, petrogenic, and pyrogenic sources. People can be exposed to PAHs through ingestion or dermal contact with contaminated sediments or through ingestion of finfish and shellfish exposed to contaminated sediments. Although more than 100 PAHs have been identified, human exposure and risk are commonly evaluated for 18 individual PAHs. Other PAHs, such as alkylated PAHs, likely contribute to biological activity of environmental PAH mixtures; however, insufficient toxicity data are available to quantify their potential risk. This article presents an initial evaluation of the potential for human health risk from exposure to alkylated PAHs in sediment and fish. Individual alkylated PAHs have been observed to have potentially mutagenic, tumor-promoting, or carcinogenic activity. However, except for 1-and 2-methylnaphthalene, insufficient toxicity data are available to quantify toxicity or cancer risk from exposure to individual alkylated PAHs or mixtures of alkylated PAHs. This article describes a proposed strategy to better understand the potential human health risk from exposure to alkylated PAHs. Implementation of this strategy will contribute to evaluations of human exposure to complex PAH mixtures in the environment.     

Unusual N-glycan structures required for trafficking Toxoplasma gondii GAP50 to the inner membrane complex regulate host cell entry through parasite motility

Toxoplasma gondii motility, which is essential for host cell entry, migration through host tissues, and invasion, is a unique form of actin-dependent gliding. It is powered by a motor complex mainly composed of myosin heavy chain A, myosin light chain 1, gliding associated proteins GAP45, and GAP50, the only integral membrane anchor so far described. In the present study, we have combined glycomic and proteomic approaches to demonstrate that all three potential N-glycosylated sites of GAP50 are occupied by unusual N-glycan structures that are rarely found on mature mammalian glycoproteins. Using site-directed mutagenesis, we show that N-glycosylation is a prerequisite for GAP50 transport from the endoplasmic reticulum to the Golgi apparatus and for its subsequent delivery into the inner complex membrane. Assembly of key partners into the gliding complex, and parasite motility are severely impaired in the unglycosylated GAP50 mutants. Furthermore, comparative affinity purification using N-glycosylated and unglycosylated GAP50 as bait identified three novel hypothetical proteins including the recently described gliding associated protein GAP40, and we demonstrate that N-glycans are required for efficient binding to gliding partners. Collectively, these results provide the first detailed analyses of T. gondii N-glycosylation functions that are vital for parasite motility and host cell entry.     

Arachidonic acid-induced human platelet aggregation independent of cyclooxygenase and lipoxygenase

It is generally agreed that arachidonic acid (20:4ω6) can stimulate platelet aggregation after conversion to prostaglandin G₂ and H₂ and thence to thromboxane A₂. This action is prevented by cyclooxygenase inhibitors. Washed platelets were isolated on metrizamide gradient and resuspended in a Ca²⁺-free buffer. Their stimulation by C 20:4 6 was followed by ¹⁴C serotonin (5HT) release, thromboxane (TX) synthesis and an increase of light transmission, not dependent on aggregation, accompanied by slight lysis (14%). The addition of extrinsic Ca²⁺ suppressed lysis and allowed the formation of aggregates. Under these conditions, cyclooxygenase inhibitors such as acetyl salicylic acid, indomethacin or flurbiprofen totally suppressed TX synthesis without preventing platelet aggregation or [¹⁴C]-5HT release. Other C 20 polyunsaturated fatty acids could not substituted for C 20:4ω6 in inducing aggregation, and Ca²⁺ was found to be a prerequesite for protection of the cell against lysis as well as for aggregation in the absence or TX formation. The use fo the lipoxygenase inhibitor BW 755 C did not prevent C 20:4ω6-induced aggregation of aspirin-treated platelets, suggesting that the phenomenon was independent of this pathway also. The total suppression of oxidative metabolism with these inhibitors was verified by the analysis of icosanoids using glass capillary column gas chromatography. It is suggested that under these condition, C 20:4ω6-induced platelet aggregation might be due to an increased membrane permeability to Ca²⁺ induced by this fatty acid in the absence of oxidation.     

Cell type-specific genotoxic effects of intermittent extremely low-frequency electromagnetic fields

The issue of adverse health effects of extremely low-frequency electromagnetic fields (ELF-EMFs) is highly controversial. Contradictory results regarding the genotoxic potential of ELF-EMF have been reported in the literature. To test whether this controversy might reflect differences between the cellular targets examined we exposed cultured cells derived from different tissues to an intermittent ELF-EMF (50 Hz sinusoidal, 1 mT) for 1-24h. The alkaline and neutral comet assays were used to assess ELF-EMF-induced DNA strand breaks. We could identify three responder (human fibroblasts, human melanocytes, rat granulosa cells) and three non-responder cell types (human lymphocytes, human monocytes, human skeletal muscle cells), which points to the significance of the cell system used when investigating genotoxic effects of ELF-EMF.