A new role for PGRP-S (Tag7) in immune defense: lymphocyte migration is induced by a chemoattractant complex of Tag7 with Mts1

PGRP-S (Tag7) is an innate immunity protein involved in the antimicrobial defense systems, both in insects and in mammals. We have previously shown that Tag7 specifically interacts with several proteins, including Hsp70 and the calcium binding protein S100A4 (Mts1), providing a number of novel cellular functions. Here we show that Tag7–Mts1 complex causes chemotactic migration of lymphocytes, with NK cells being a preferred target. Cells of either innate immunity (neutrophils and monocytes) or acquired immunity (CD4⁺ and CD8⁺ lymphocytes) can produce this complex, which confirms the close connection between components of the 2 branches of immune response.     

<Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> inhibits <Emphasis Type="Italic">in-vitro Candida</Emphasis> biofilm development

Background  

Elucidation of the communal behavior of microbes in mixed species biofilms may have a major impact on understanding infectious diseases and for the therapeutics. Although, the structure and the properties of monospecies biofilms and their role in disease have been extensively studied during the last decade, the interactions within mixed biofilms consisting of bacteria and fungi such as Candida spp. have not been illustrated in depth. Hence, the aim of this study was to evaluate the interspecies interactions of Pseudomonas aeruginosa and six different species of Candida comprising C. albicans, C. glabrata, C. krusei, C. tropicalis, C. parapsilosis, and C. dubliniensis in dual species biofilm development.     

Molecular determinants of caste differentiation in the highly eusocial honeybee <Emphasis Type="Italic">Apis mellifera</Emphasis>

Background  

In honeybees, differential feeding of female larvae promotes the occurrence of two different phenotypes, a queen and a worker, from identical genotypes, through incremental alterations, which affect general growth, and character state alterations that result in the presence or absence of specific structures. Although previous studies revealed a link between incremental alterations and differential expression of physiometabolic genes, the molecular changes accompanying character state alterations remain unknown.     

Mitochondrial haplotype diversity in the tortoise species <Emphasis Type="Italic">Testudo graeca</Emphasis> from North Africa and the Middle East

Background  

To help conservation programs of the endangered spur-thighed tortoise and to gain better insight into its systematics, genetic variation and evolution in the tortoise species Testudo graeca (Testudines: Testudinidae) was investigated by sequence analysis of a 394-nucleotide fragment of the mitochondrial 12S rRNA gene for 158 tortoise specimens belonging to the subspecies Testudo graeca graeca, Testudo graeca ibera, Testudo graeca terrestris, and a newly recognized subspecies Testudo graeca whitei. A 411-nucleotide fragment of the mitochondrial D-loop was additionally sequenced for a subset of 22 T. graeca, chosen because of their 12S gene haplotype and/or geographical origin.     

History and dynamics of the crown-of-thorns starfish Acanthaster planci (L.) in the Suva area,Fiji

Annual recruitment of Acanthaster planci over a 13 year period in a known juvenile refuge substratum on Suva Reef was very patchy in time and space. Macroscale recruitment events resulted in outbreaks over many thousands of hectares over 100 km of coastline whereas localised but intensive mesoscale events resulted in concenrated aggregations over areas of several tens of hectares. A very low level of recruitment occurred in most years but three intensive, macroscale recruitment events occurred in 1977, 1984 and 1987, and two localised but intensive recruitment events occurred in 1982 and 1983. Annual recruitment of A. planci between 1975–89 had no overt relationship with rainfall events, as proposed in the terrestrial run-off hypothesis on the cause of primary out-breaks. Growth rates within monitored cohorts were highly variable, but mean growth rates of two cohorts 1984 and 1987 were relatively similar. Mortality rates of three monitored cohorts were variable. Longevity of the 1977 cohort was 7–8 years, while that of the 1984 cohort was 2–3 years. Mortality of the 1987 cohort has been low to date (i.e. 4 years of age). Disease, attributed to an undescribed sporozoan pathogen, was responsible for two mass mortalities in the 1984 cohort, in 1984 and in 1986, and eventually resulted in the extinction of this cohort. Anecdotal reports indicate that outbreaks of A. planci are increasing in frequency and severity. According to Fijian reef fishermen, the starfish were low to moderate in abundance in the Suva area from the 1920s to the 1960s. A progressive build up occurred on some reefs in 1963–67 leading to a major outbreak episode from 1967–1971. The outbreaks were in a chronic phase between 1977–1989. Our findings demonstrate that there is no invariable pattern or process involved in the population dynamics of A. planci and that a single explanation of the A. planci phenomenon is therefore unlikely.     

The Onset of Song Learning and Song Tutor Selection in Fledgling Zebra Finches

We investigated song development in the pre‐independent zebra finch (aged 15–35 d), a period when neural pathways for song learning and production are forming and social influences outside the family are limited. Expt 1 investigated the onset and the minimum duration of tutoring needed for song learning in fledglings. We found most begin to learn song from 25 d of age and need about 10 d contact with the father tutor to make accurate copies. This onset corresponds with major developments in the formation of the neural circuitry implicated in song acquisition. Subsong also begins on day 25 suggesting that the sensory and motor phases of song learning fully overlap in the zebra finch. Our findings support the hypothesis that the song circuitry is fully functional by 35 d of age and the sensitive phase for zebra finches extends therefore from about days 25–65. However, only the first 10 d of this period are necessary to learn a tutor's song with fair accuracy. Expt 2 investigated the role of the paternal bond, spatial proximity and mating status in a fledgling's choice of song tutor where the father was the sole parent. Young chose the father over single unrelated males (expt 2a) or unrelated males in company with their female partners (expt 2b). Given the close spatial proximity of both potential tutors to the fledglings it is probably the filial bond, established via paternal care that is the cause of this preference. Zebra finches sing the same song phrase in two contrasting contexts: female‐directed song during pre‐copulatory courtship and undirected song where no female or display is involved. In expt 3 we tested the song learning preference of pre‐independent young for two categories of non‐paternal tutors: those singing predominantly female‐directed song and those singing exclusively undirected song. There was a small, but significant, preference for fledgling zebra finches to copy songs from males that sang female‐directed song. This preference is consistent with the hypothesis that young males not only learn the acoustic features of their tutor's song but also the visual and dynamic movements that constitute the courtship display.     

A network-based approach to identify substrate classes of bacterial glycosyltransferases

Background

Bacterial interactions with the environment- and/or host largely depend on the bacterial glycome. The specificities of a bacterial glycome are largely determined by glycosyltransferases (GTs), the enzymes involved in transferring sugar moieties from an activated donor to a specific substrate. Of these GTs their coding regions, but mainly also their substrate specificity are still largely unannotated as most sequence-based annotation flows suffer from the lack of characterized sequence motifs that can aid in the prediction of the substrate specificity.

Results

In this work, we developed an analysis flow that uses sequence-based strategies to predict novel GTs, but also exploits a network-based approach to infer the putative substrate classes of these predicted GTs. Our analysis flow was benchmarked with the well-documented GT-repertoire of Campylobacter jejuni NCTC 11168 and applied to the probiotic model Lactobacillus rhamnosus GG to expand our insights in the glycosylation potential of this bacterium. In L. rhamnosus GG we could predict 48 GTs of which eight were not previously reported. For at least 20 of these GTs a substrate relation was inferred.

Conclusions

We confirmed through experimental validation our prediction of WelI acting upstream of WelE in the biosynthesis of exopolysaccharides. We further hypothesize to have identified in L. rhamnosus GG the yet undiscovered genes involved in the biosynthesis of glucose-rich glycans and novel GTs involved in the glycosylation of proteins. Interestingly, we also predict GTs with well-known functions in peptidoglycan synthesis to also play a role in protein glycosylation.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-349) contains supplementary material, which is available to authorized users.