Comparing infant and juvenile behavior in bonobos (Pan paniscus) and chimpanzees (Pan troglodytes): a preliminary study

The dichotomy between the two Pan species, the bonobo (Pan paniscus) and chimpanzee (Pan troglodytes) has been strongly emphasized until very recently. Given that most studies were primarily based on adult individuals, we shifted the “continuity versus discontinuity” discussion to the infant and juvenile stage. Our aim was to test quantitatively, some conflicting statements made in literature considering species differences between immature bonobos and chimpanzees. On one hand it is suggested that infant bonobos show retardation in motor and social development when compared with chimpanzees. Additionally it is expected that the weaning process is more traumatic to chimpanzee than bonobo infants. But on the other hand the development of behaviors is expected to be very similar in both species. We observed eight mother–infant pairs of each species in several European zoos. Our preliminary research partially confirms that immature chimpanzees seem spatially more independent, spending more time at a larger distance from their mother than immature bonobos. However, the other data do not seem to support the hypothesis that bonobo infants show retardation of motor or social development. The development of solitary play, environmental exploration, social play, non-copulatory mounts and aggressive interactions do not differ between the species. Bonobo infants in general even groom other group members more than chimpanzee infants. We also found that older bonobo infants have more nipple contact than same aged chimpanzees and that the weaning process seems to end later for bonobos than for immature chimpanzee. Additionally, although immature bonobos show in general more signs of distress, our data suggest that the weaning period itself is more traumatic for chimpanzees.     

Characterization of three human oligodendroglial cell lines as a model to study oligodendrocyte injury: Morphology and oligodendrocyte-specific gene expression

Oligodendrocytes, the myelin-forming cells of the central nervous system, are the target of pathogenic immune responses in multiple sclerosis. Primary cultures of human oligodendrocytes have been used to unravel the cellular and molecular mechanisms of immune-mediated injury of oligodendrocytes. However, these studies are hampered by the limited availability of viable human brain tissue. The present study was aimed at comparing the morphological and biochemical characteristics of the human oligodendroglial cell lines HOG, MO3.13 and KG-1C. We have determined oligodendrocyte-associated features of these lines and analyzed the degree to which they can be used as a model of human oligodendrocytes arrested at specific developmental stages. The oligodendroglial cell lines all exhibited markers of immature oligodendrocytes, such as CNPase and GalC, but not the astrocytic marker GFAP. Differentiation could be induced in HOG and MO3.13 cells, as was seen through a decrease in proliferation, an increase in process extension without formation of myelin sheets and up-regulation of genes associated with mature oligodendrocytes such as MBP and MOG. Microarray analysis revealed the expression of MAG, MOBP and OMG genes in HOG cells. The KG-1C cells displayed poor growth characteristics in the recommended conditions. In conclusion, our data show that the oligodendroglial cell lines HOG and MO3.13 can be used as a model of human oligodendrocytes ‘arrested’ in an immature developmental stage. Culturing in appropriate medium can induce further differentiation of these cells. These cell lines can therefore be applied as a model to study immune-mediated injury of oligodendrocytes in relation to disease.     

The MADS domain protein DIANA acts together with AGAMOUS-LIKE80 to specify the central cell in Arabidopsis ovules

MADS box genes in plants consist of MIKC-type and type I genes. While MIKC-type genes have been studied extensively, the functions of type I genes are still poorly understood. Evidence suggests that type I MADS box genes are involved in embryo sac and seed development. We investigated two independent T-DNA insertion alleles of the Arabidopsis thaliana type I MADS box gene AGAMOUS-LIKE61 (AGL61) and showed that in agl61 mutant ovules, the polar nuclei do not fuse and central cell morphology is aberrant. Furthermore, the central cell begins to degenerate before fertilization takes place. Although pollen tubes are attracted and perceived by the mutant ovules, neither endosperm development nor zygote formation occurs. AGL61 is expressed in the central cell during the final stages of embryo sac development. An AGL61:green fluorescent protein–β-glucoronidase fusion protein localizes exclusively to the polar nuclei and the secondary nucleus of the central cell. Yeast two-hybrid analysis showed that AGL61 can form a heterodimer with AGL80 and that the nuclear localization of AGL61 is lost in the agl80 mutant. Thus, AGL61 and AGL80 appear to function together to differentiate the central cell in Arabidopsis. We renamed AGL61 DIANA, after the virginal Roman goddess of the hunt.     

Cryo electron tomography of vitrified fibroblasts: microtubule plus ends in situ

Mouse embryonic fibroblasts (MEFs) are cells that have highly suitable biophysical properties for cellular cryo electron tomography. MEFs can be grown directly on carbon supported by EM grids. They stretch out and grow thinner than 500 nm over major parts of the cell, attaining a minimal thickness of 50 nm at their cortex. This facilitates direct cryo-fixation by plunge-freezing and high resolution cryo electron tomography. Both by direct cryo electron microscopy projection imaging and cryo electron tomography of vitrified MEFs we visualized a variety of cellular structures like ribosomes, vesicles, mitochondria, rough endoplasmatic reticulum, actin filaments, intermediate filaments and microtubules.MEFs are primary cells that closely resemble native tissue and are highly motile. Therefore, they are attractive for studying cytoskeletal elements. Here we report on structural investigations of microtubule plus ends. We were able to visualize single frayed protofilaments at the microtubule plus end in vitrified fibroblasts using cryo electron tomography. Furthermore, it appeared that MEFs contain densities inside their microtubules, although 2.5–3.5 times less than in neuronal cells [Garvalov, B.K., Zuber, B., Bouchet-Marquis, C., Kudryashev, M., Gruska, M., Beck, M., Leis, A., Frischknecht, F., Bradke, F., Baumeister, W., Dubochet, J., and Cyrklaff, M. 2006. Luminal particles within cellular microtubules. J. Cell Biol. 174, 759–765]. Projection imaging of cellular microtubule plus ends showed that 40% was frayed, which is two times more than expected when compared to microtubule growth and shrinkage rates in MEFs. This suggests that frayed ends might be stabilized in the cell cortex.     

Tumor Necrosis Factor-α +489G/A gene polymorphism is associated with chronic obstructive pulmonary disease

Pulmonary surfactant is a complex mixture of phospholipids and proteins, which is present in the alveolar lining fluid and is essential for normal lung function. Alterations in surfactant composition have been reported in several interstitial lung diseases (ILDs). Furthermore, a mutation in the surfactant protein C gene that results in complete absence of the protein has been shown to be associated with familial ILD. The role of surfactant in lung disease is therefore drawing increasing attention following the elucidation of the genetic basis underlying its surface expression and the proof of surfactant abnormalities in ILD.     

Birbeck granules are subdomains of endosomal recycling compartment in human epidermal Langerhans cells, which form where Langerin accumulates.

Birbeck granules are unusual rod-shaped structures specific to epidermal Langerhans cells, whose origin and function remain undetermined. We investigated the intracellular location and fate of Langerin, a protein implicated in Birbeck granule biogenesis, in human epidermal Langerhans cells. In the steady state, Langerin is predominantly found in the endosomal recycling compartment and in Birbeck granules. Langerin internalizes by classical receptor-mediated endocytosis and the first Birbeck granules accessible to endocytosed Langerin are those connected to recycling endosomes in the pericentriolar area, where Langerin accumulates. Drug-induced inhibition of endocytosis results in the appearance of abundant open-ended Birbeck granule-like structures appended to the plasma membrane, whereas inhibition of recycling induces Birbeck granules to merge with a tubular endosomal network. In mature Langerhans cells, Langerin traffic is abolished and the loss of internal Langerin is associated with a concomitant depletion of Birbeck granules. Our results demonstrate an exchange of Langerin between early endosomal compartments and the plasma membrane, with dynamic retention in the endosomal recycling compartment. They show that Birbeck granules are not endocytotic structures, rather they are subdomains of the endosomal recycling compartment that form where Langerin accumulates. Finally, our results implicate ADP-ribosylation factor proteins in Langerin trafficking and the exchange between Birbeck granules and other endosomal membranes.     

Maize ATR safeguards genome stability during kernel development to prevent early endosperm endocycle onset and cell death

The ataxia-telangiectasia mutated (ATM) and ATM and Rad3-related (ATR) kinases coordinate the DNA damage response. The roles described for Arabidopsis thaliana ATR and ATM are assumed to be conserved over other plant species, but molecular evidence is scarce. Here, we demonstrate that the functions of ATR and ATM are only partially conserved between Arabidopsis and maize (Zea mays). In both species, ATR and ATM play a key role in DNA repair and cell cycle checkpoint activation, but whereas Arabidopsis plants do not suffer from the absence of ATR under control growth conditions, maize mutant plants accumulate replication defects, likely due to their large genome size. Moreover, contrarily to Arabidopsis, maize ATM deficiency does not trigger meiotic defects, whereas the ATR kinase appears to be crucial for the maternal fertility. Strikingly, ATR is required to repress premature endocycle onset and cell death in the maize endosperm. Its absence results in a reduction of kernel size, protein and starch content, and a stochastic death of kernels, a process being counteracted by ATM. Additionally, while Arabidopsis atr atm double mutants are viable, no such mutants could be obtained for maize. Therefore, our data highlight that the mechanisms maintaining genome integrity may be more important for vegetative and reproductive development than previously anticipated.

Differently from Arabidopsis, ATR activity in maize plays an essential role under control growth conditions, ensuring genome stability during kernel Development.     

Occurrence and genetic diversity of Bacillus anthracis strains isolated in an active wool-cleaning factory

Culturable microorganisms from various samples taken at an active factory performing wool and goat hair cleaning were isolated and analyzed. Bacillus anthracis was found in air filter dust, wastewater, and goat hairs, where it accounted for approximately 1% of the total counts of viable bacteria. Consistent with the countries of origin of the processed material (South Caucasian and Middle Eastern), all B. anthracis isolates belonged to the same phylogenetic cluster, as determined by variable-number tandem repeat (VNTR) typing at eight loci. Within this cluster, five closely related VNTR subtypes could be identified, of which two were previously unreported. Additional diversity was observed when more sensitive genetic markers were assayed, demonstrating the multifocal nature of goat hair contamination. Goat hair originating from areas where anthrax is endemic remains a material with high biological risk for modern woolworkers.     

Pesticide exposure strongly enhances parasite virulence in an invertebrate host model

Parasites are a common and constant threat to organisms at all levels of phyla. The virulence of a parasite, defined as the impact on survival and reproduction of its host, depends on the specific host–parasite combination and can also be influenced by environmental conditions. Environmental pollution might be an additional factor influencing host–parasite interactions. We here aimed to test whether the combined stress of pollutant exposure and parasite challenge results in stronger impacts on host organisms than expected from the single stressors applied alone. We used the water flea Daphnia magna and two of its endoparasites, the bacterium Pasteuria ramosa and the microsporidium Flabelliforma magnivora, as invertebrate host–parasite models. For each parasite, we tested in a full‐factorial design for interactions between parasitism and pollution using the neurotoxic pesticide carbaryl as a model substance. Sublethal concentrations of the pesticide synergistically enhanced the virulence of both parasites by increasing host mortality. Furthermore, host castration induced by P. ramosa was accelerated by carbaryl exposure. These effects likely reflect decreased host resistance due to direct or indirect immunosuppressive activity of carbaryl. The present study provides experimental evidence that the in vivo development of infectious diseases can be influenced by a pesticide at environmentally realistic concentrations. This implies that host–parasite interactions and subsequently co‐evolution might be influenced by environmental pollution at toxicant concentrations being sublethal to parasite‐free hosts. Standard toxicity testing as employed in the current way of conducting ecological risk assessments for anthropogenic substances does not consider natural antagonists such as infectious diseases, and thereby likely underestimates the impact these substances may pose to natural populations in the environment.