Incipient morphological specializations associated with fossorial life in the skull of ground squirrels (Sciuridae,Rodentia)

Anatomical and biological specializations have been studied extensively in fossorial rodents, especially in subterranean species, such as mole-rats or pocket-gophers. Sciurids (i.e., squirrels) are mostly known for their diverse locomotory behaviors, and encompass many arboreal species. They also include less specialized fossorial species, such as ground squirrels that are mainly scratch diggers. The skull of ground squirrels remains poorly investigated in a fossorial context, while it may reflect incipient morphological specializations associated with fossorial life, especially due to the putative use of incisors for digging in some taxa. Here, we present the results of a comparative analysis of the skull of five fossorial sciurid species, and compare those to four arboreal sciurids, one arboreal/fossorial sciurid and one specialized fossorial aplodontiid. The quantification of both cranial and mandibular shapes, using three dimensional geometric morphometrics, reveals that fossorial species clearly depart from arboreal species. Fossorial species from the Marmotini tribe, and also Xerini to a lesser extent, show widened zygomatic arches and occipital plate on the cranium, and a wide mandible with reduced condyles. These shared characteristics, which are present in the aplodontiid species, likely represent fossorial specializations rather than relaxed selection on traits related to the ancestral arboreal condition of sciurids. Such cranial and mandibular configurations combined with proodont incisors might also be related to the frequent use of incisors for digging (added to forelimbs), especially in Marmotini evolving in soft to hard soil conditions. This study provides some clues to understand the evolutionary mechanisms shaping the skull of fossorial rodents, in relation to the time spent underground and to the nature of the soil.     

The paleobiology of two adult skeletons from Baousso da Torre (Bausu da Ture) (Liguria,Italy): Implications for Gravettian lifestyle

This article presents the main skeletal characteristics of the two largely unpublished Gravettian adult skeletons from Baousso da Torre (Liguria, Italy). BT1 and BT2 were two adult tall males, who died aged respectively between 20 and 50 years, and between 20 and 30 years. Their body proportions fall within the range of variation known for the middle Upper Paleolithic, and their skeletal remains are characterized by considerable osteometric values, which fall consistently in the upper part of the Upper Paleolithic male sample variation. They show a high degree of upper limb lateralization, implying that they were likely involved in strenuous and/or repetitive unimanual tasks. They also exhibit very robust lower limbs, likely related to repeated long-distance travels in mountainous terrains. These results are in total agreement with previous hypotheses on Late Pleistocene population behavioral patterns.     

Performance of Ooencyrtus kuvanae (Hymenoptera: Encyrtidae) on two host species,Halyomorpha halys and Philosamia ricini

The brown marmorated stink bug, Halyomorpha halys, is an invasive agricultural pest of fruit trees and vegetables. Egg parasitoids play a key role in the reducing of H. halys populations. Ooencyrtus kuvanae (Howard) (Hymenoptera: Encyrtidae) can parasitize H. halys and complete its life cycle in this host species. Many factors can influence this parasitoid–host relationship. Of these factors, we evaluated the effect of female age, exposure time, and host species on the biological characteristics and fecundity of O. kuvanae reared on eggs of H. halys as well as another previously known host Philosamia ricini (Lepidoptera: Saturniidae). In this study, we used a 3-year-old laboratory colony of O. kuvanae. Parasitism rates positively affected by exposure time in P. ricini. The highest parasitism rates were obtained in 5- and 7-day-old females of both hosts. The highest emergence rates were recorded on P. ricini for 5- and 7-day-old female P. ricini (81.8% and 84.8%, respectively). The development time of O. kuvanae ranged from 18.4 to 19.1 days on H. halys and 17.7 to 18.3 days on P. ricini. The longevity of O. kuvanae that were provided honey was 38.5 and 47.8 days on H. halys and P. ricini, respectively. The longevity of O. kuvanae that were not provided honey was 2.3 and 2.8 days on H. halys and P. ricini, respectively. The sex ratio was male-biased (36.5% female) on H. halys and female-biased (55.2% female) on P. ricini. Fecundity of O. kuvanae was 37.7 and 59.6 progeny per female for H. halys and P. ricini, respectively. The performance of O. kuvanae was lower when compared with its performance on the host P. ricini. Our results suggest that O. kuvanae has potential as new biological control agent for H. halys.     

Die Organisation des optischen Feldes bei der Biene. II

Ohne Zusammenfassung     

Robustness of epithelial sealing is an emerging property of local ERK feedback driven by cell elimination

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Ultra-sensitive immunodetection of 5'methyl cytosine for DNA methylation analysis on oligonucleotide microarrays.

For the determination of methylation levels in genomic regulatory DNA sequences a high-sensitive assay for detecting 5'methyl-cytosines (5'mC) in non-bisulfite-treated DNA has been established. The system is designed for the application of immunofluorescence using a monoclonal antibody that specifically recognizes 5'mC in single-stranded DNA hybridized to oligonucleotide microarrays. For assay readout an ultra-sensitive fluorescence scanner with submicrometer resolution was used. To minimize autofluorescence 150-microm thin glass slides with an aldehyde-functionalized surface were developed. These methodological improvements allowed the detection of 5'mC in synthetic oligonucleotides hybridized to microarrays with atto molar analytical sensitivity. Using enzymatic fragmented genomic DNA from myeloid leukemia tumor cell lines differences in the methylation status of gene regulatory sequences for E-cadherin, p15/CDKN2b and p16/CDKN2a were demonstrated. Thus, this novel technique can potentially be used for DNA methylation analysis in various scientific fields.     

Peptidoglycan maturation enzymes affect flagellar functionality in bacteria

The flagellar machinery is a highly complex organelle composed of a free rotating flagellum and a fixed stator that converts energy into movement. The assembly of the flagella and the stator requires interactions with the peptidoglycan layer through which the organelle has to pass for externalization. Lytic transglycosylases are peptidoglycan degrading enzymes that cleave the sugar backbone of peptidoglycan layer. We show that an endogenous lytic transglycosylase is required for full motility of Helicobacter pylori and colonization of the gastric mucosa. Deficiency of motility resulted from a paralysed phenotype implying an altered ability to generate flagellar rotation. Similarly, another Gram‐negative pathogen Salmonella typhimurium and the Gram‐positive pathogen Listeria monocytogenes required the activity of lytic transglycosylases, Slt or MltC, and a glucosaminidase (Auto), respectively, for full motility. Furthermore, we show that in absence of the appropriate lytic transglycosylase, the flagellar motor protein MotB from H. pylori does not localize properly to the bacterial pole. We present a new model involving the maturation of the surrounding peptidoglycan for the proper anchoring and functionality of the flagellar motor.