Seven species of house geckos occur across the scattered islands of the Indian Ocean. Two of these,
Hemidactylus frenatus
and
H. parvimaculatus
are both widespread and possess distribution profiles ...that suggest pre-European, or perhaps natural dispersal to some islands. Of these, only
H. frenatus
currently has sufficient molecular data to begin exploring dispersal patterns. This species is one of the most successful reptile colonists, as demonstrated by its global, pantropical distribution. While in some areas, such as Australia and continental South America, its dispersal patterns are both recent and well-known, early historical records of
Hemidactylus
in the Indian Ocean islands suggest earlier and/or potentially non-human-mediated dispersals. Here, we reviewed the historical literature and combined those reports with an assessment of mitochondrial DNA diversity of a global sampling of
H. frenatus
samples that included modern and museum specimens. Our results corroborate previous studies and demonstrate the relatively high diversity within this species’ native range in Southeast Asia. In addition, the phylogenetic analysis suggests both a potential cryptic species complex, as well as global geographic structuring of different
H. frenatus
mitochondrial lineages. This has important implications for many comparative studies of this complex. Frequent and ongoing dispersals and colonizations complicate the identification of potentially older migration patterns. Further assessments including additional samples and analyses of additional genetic markers are necessary to disentangle older from more recent dispersals within this intriguing species.
Island systems offer excellent opportunities for studying the evolutionary histories of species by virtue of their restricted size and easily identifiable barriers to gene flow. However, most studies ...investigating evolutionary patterns and processes shaping biotic diversification have focused on more recent (emergent) rather than ancient oceanic archipelagos. Here, we focus on the granitic islands of the Seychelles, which are unusual among island systems because they have been isolated for a long time and are home to a monophyletic radiation of caecilian amphibians that has been separated from its extant sister lineage for ca. 65-62 Ma. We selected the most widespread Seychelles caecilian species, Hypogeophis rostratus, to investigate intraspecific morphological and genetic (mitochondrial and nuclear) variation across the archipelago (782 samples from nine islands) to identify patterns and test processes that shaped their evolutionary history within the Seychelles.
Overall a signal of strong geographic structuring with distinct northern- and southern-island clusters were identified across all datasets. We suggest that these distinct groups have been isolated for ca. 1.26 Ma years without subsequent migration between them. Populations from the somewhat geographically isolated island of Frégate showed contrasting relationships to other islands based on genetic and morphological data, clustering alternatively with northern-island (genetic) and southern-island (morphological) populations.
Although variation in H. rostratus across the Seychelles is explained more by isolation-by-distance than by adaptation, the genetic-morphological incongruence for affinities of Frégate H. rostratus might be caused by local adaptation over-riding the signal from their vicariant history. Our findings highlight the need of integrative approaches to investigate fine-scale geographic structuring to uncover underlying diversity and to better understand evolutionary processes on ancient, continental islands.
Mast cells that are in close proximity to autonomic and enteric nerves release several mediators that cause neuronal hyperexcitability.
This study examined whether mast cell tryptase evokes acute and ...long-term hyperexcitability in submucosal neurons from the
guinea-pig ileum by activating proteinase-activated receptor 2 (PAR2) on these neurons. We detected the expression of PAR2
in the submucosal plexus using RT-PCR. Most submucosal neurons displayed PAR2 immunoreactivity, including those colocalizing
VIP. Brief (minutes) application of selective PAR2 agonists, including trypsin, the activating peptide SL-NH 2 and mast cell tryptase, evoked depolarizations of the submucosal neurons, as measured with intracellular recording techniques.
The membrane potential returned to resting values following washout of agonists, but most neurons were hyperexcitable for
the duration of recordings (> 30 minâhours) and exhibited an increased input resistance and amplitude of fast EPSPs. Trypsin,
in the presence of soybean trypsin inhibitor, and the reverse sequence of the activating peptide (LR-NH 2 ) had no effect on neuronal membrane potential or long-term excitability. Degranulation of mast cells in the presence of antagonists
of established excitatory mast cell mediators (histamine, 5-HT, prostaglandins) also caused depolarization, and following
washout of antigen, long-term excitation was observed. Mast cell degranulation resulted in the release of proteases, which
desensitized neurons to other agonists of PAR2. Our results suggest that proteases from degranulated mast cells cleave PAR2
on submucosal neurons to cause acute and long-term hyperexcitability. This signalling pathway between immune cells and neurons
is a previously unrecognized mechanism that could contribute to chronic alterations in visceral function.
Small RNA (sRNA) profiling of Extracellular Vesicles (EVs) by Next‐Generation Sequencing (NGS) often delivers poor outcomes, independently of reagents, platforms or pipelines used, which contributes ...to poor reproducibility of studies. Here we analysed pre/post‐sequencing quality controls (QC) to predict issues potentially biasing biological sRNA‐sequencing results from purified human milk EVs, human and mouse EV‐enriched plasma and human paraffin‐embedded tissues. Although different RNA isolation protocols and NGS platforms were used in these experiments, all datasets had samples characterized by a marked removal of reads after pre‐processing. The extent of read loss between individual samples within a dataset did not correlate with isolated RNA quantity or sequenced base quality. Rather, cDNA electropherograms revealed the presence of a constant peak whose intensity correlated with the degree of read loss and, remarkably, with the percentage of adapter dimers, which were found to be overrepresented sequences in high read‐loss samples. The analysis through a QC pipeline, which allowed us to monitor quality parameters in a step‐by‐step manner, provided compelling evidence that adapter dimer contamination was the main factor causing batch effects. We concluded this study by summarising peer‐reviewed published workflows that perform consistently well in avoiding adapter dimer contamination towards a greater likelihood of sequencing success.
Small bowel tumours are rare, representing about 0.5% of all tumours and about 3% of gastrointestinal tract tumours. The low prevalence contrasts with the vast surface area of the small intestine, ...which accounts for over 90% of the surface area of the digestive tract. The frequency of small tumours decreases from proximal to distal, and therefore from the duodenum to the ileum. The histological types differ in terms of prevalence according to the affected segment, with adenocarcinoma being the most frequent in the duodenum and jejunum and carcinoid tumour in the ileum. Diagnosis is challenging due to clinical non-specificity, low prevalence and a low level of suspicion. Schwannomas are typically benign tumours that arise from Schwann's cells and are rarely found in the small intestine. It is even more rare to find them together with another histological type, namely adenocarcinoma. No cases have been reported in the literature of these lesions occurring in the small intestine simultaneously. Further studies are needed to clarify the underlying pathophysiology of these synchronous tumours. The authors present the case of an 86-year-old female patient admitted for high intestinal subocclusion, with refractory vomiting and involuntary weight loss. Two synchronous lesions in the digestive tract were identified: an adenocarcinoma in the duodenum and a schwannoma in the ileum. The patient underwent surgical resection of both lesions. A high level of suspicion combined with a multidisciplinary approach is necessary for timely diagnosis and surgical resolution.
Small bowel neoplasms are rare and clinically non-specific; in addition, diagnosis is difficult due to imaging artifacts and tumour inaccessibility for biopsy for definitive histological diagnosis.Gastrointestinal schwannomas are rare and the pathophysiology of synchrony with other histological subtypes remains to be clarified.A multidisciplinary approach from the beginning is important for a timely diagnosis and better outcome.
The extent of social behaviour among reptiles is underappreciated. Two types of aggregations are recognized in lizards: ecological and social, i.e., related to the attraction to a site or to animals ...of the same species, respectively. As most lizards are territorial, aggregations increase the probability of aggressive interactions among individuals, a density-dependent behaviour.
After some spurious observations of aggregation behaviour in the endemic Cabo Verde nocturnal gecko
we conducted a field-based study in order to thoroughly characterize it. We sampled 48 transects and 40 10 × 10 m quadrats on São Vicente Island to describe the incidence, size and composition of aggregations and to study the effect of gecko and refuge density, plus refuge quality, on refuge sharing. We hypothesize that when density of animals and scarcity of high-quality refuges is higher, lizards have increased probability of aggregating. We also predict a consistent pattern of size and composition of groups (male-female pairs, only one adult male per group) throughout the year if there is a selected behaviour to avoid agonistic interactions, and low thermal advantage to aggregating individuals.
We present one of the first evidences of aggregation for Phyllodactylidae geckos. We found that
forms aggregations around 30-40% of the time, and that refuges are almost always shared by a female-male pair, sometimes with a juvenile, probably a mechanism to avoid aggressive interactions. We also observed that refuge sharing is dependent on refuge quality, as medium-large (thermally more stable and positively selected) rocks are shared much more frequently than small ones, but independent of adult sizes. Refuge sharing is also directly related to the density of geckos and inversely related to the density of high-quality refuges. We found no relation between body temperatures of geckos and refuge sharing when controlling the effect of rock/air temperature, suggesting that huddling does not improve thermoregulation.
Our results suggest that in this harsh environment (rocks reach 46 °C) aggregation incidence is mainly driven by an ecological factor (scarcity of high-quality refuges) and its intersexual composition by social factors (avoidance of agonistic interactions by males, and possible increased reproductive success of the pair). This study sheds some light on the little explored gecko aggregation behaviour and other studies should follow.
Non-self gametophytic self-incompatibility (GSI) recognition system is characterized by the presence of multiple F-box genes tandemly located in the
-locus, that regulate pollen specificity. This ...reproductive barrier is present in Solanaceae, Plantaginacea and Maleae (Rosaceae), but only in
functional assays have been performed to get insight on how this recognition mechanism works. In this system, each of the encoded
-pollen proteins (called SLFs in Solanaceae and Plantaginaceae /SFBBs in Maleae) recognizes and interacts with a sub-set of non-self
-pistil proteins, called S-RNases, mediating their ubiquitination and degradation. In
there are 17
genes per
-haplotype, making impossible to determine experimentally each SLF specificity. Moreover, domain -swapping experiments are unlikely to be performed in large scale to determine
-pollen and
-pistil specificities. Phylogenetic analyses of the Petunia SLFs and those from two
genomes, suggest that diversification of
s predate the two genera separation. Here we first identify putative
genes from nine
and 10
genomes to determine how many gene lineages are present in the three genera, and the rate of origin of new
gene lineages. The use of multiple genomes per genera precludes the effect of incompleteness of the genome at the
-locus. The similar number of gene lineages in the three genera implies a comparable effective population size for these species, and number of specificities. The rate of origin of new specificities is one per 10 million years. Moreover, here we determine the amino acids positions under positive selection, those involved in SLF specificity recognition, using 10
-haplotypes with more than 11
genes. These 16 amino acid positions account for the differences of self-incompatible (SI) behavior described in the literature. When SLF and S-RNase proteins are divided according to the SI behavior, and the positively selected amino acids classified according to hydrophobicity, charge, polarity and size, we identified fixed differences between SI groups. According to the
3D structure of the two proteins these amino acid positions interact. Therefore, this methodology can be used to infer SLF/S-RNase specificity recognition.
Among the transmissible spongiform encephalopathies (TSEs), chronic wasting disease (CWD) in cervids is now a rising concern in wildlife within Europe, after the detection of the first case in Norway ...in 2016, in a wild reindeer and until June 2022 a total of 34 cases were described in Norway, Sweden and Finland. The definite diagnosis is post-mortem, performed in target areas of the brain and lymph nodes. Samples are first screened using a rapid test and, if positive, confirmed by immunohistochemistry and Western immunoblotting. The study of the genetics of the prion protein gene, PRNP, has been proved to be a valuable tool for determining the relative susceptibility to TSEs. In the present study, the exon 3 of PRNP gene of 143 samples from red deer (Cervus elaphus) and fallow deer (Dama dama) of Portugal was analysed. Three single nucleotide polymorphisms (SNPs) were found in red deer - codon A136A, codon T98A, codon Q226E - and no sequence variation was detected in fallow deer. The low genetic diversity found in our samples is compatible with previous studies in Europe. The comparison with results from North America suggests that the free-ranging deer from our study may present susceptibility to CWD, although lack of experimental data and the necessity of continuous survey are necessary to evaluate these populations.
Wild-type (wt) polyglutamine (polyQ) regions are implicated in stabilization of protein-protein interactions (PPI). Pathological polyQ expansion, such as that in human Ataxin-1 (ATXN1), that causes ...spinocerebellar ataxia type 1 (SCA1), results in abnormal PPI. For ATXN1 a larger number of interactors has been reported for the expanded (82Q) than the wt (29Q) protein.
To understand how the expanded polyQ affects PPI, protein structures were predicted for wt and expanded ATXN1, as well as, for 71 ATXN1 interactors. Then, the binding surfaces of wt and expanded ATXN1 with the reported interactors were inferred.
Our data supports that the polyQ expansion alters the ATXN1 conformation and that it enhances the strength of interaction with ATXN1 partners. For both ATXN1 variants, the number of residues at the predicted binding interface are greater after the polyQ, mainly due to the AXH domain. Moreover, the difference in the interaction strength of the ATXN1 variants was due to an increase in the number of interactions at the N-terminal region, before the polyQ, for the expanded form.
There are three regions at the AXH domain that are essential for ATXN1 PPI. The N-terminal region is responsible for the strength of the PPI with the ATXN1 variants. How the predicted motifs in this region affect PPI is discussed, in the context of ATXN1 post-transcriptional modifications.
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