Divergence in mating signals correlates with genetic distance and behavioural responses to playback

Animals use acoustic signals to defend resources against rivals and attract breeding partners. As with many biological traits, acoustic signals may reflect ancestry; closely related species often produce more similar signals than do distantly related species. Whether this similarity in acoustic signals is biologically relevant to animals is poorly understood. We conducted a playback experiment to measure the physical and vocal responses of male songbirds to the songs of both conspecific and allopatric‐congeneric animals that varied in their acoustic and genetic similarity. Our subjects were territorial males of four species of neotropical Troglodytes wrens: Brown‐throated Wrens (Troglodytes brunneicollis), Cozumel Wrens (T. beani), Clarion Wrens (T. tanneri) and Socorro Wrens (T. sissonii). Our results indicate that birds respond to playback of both conspecific and allopatric‐congeneric animals; that acoustic differences increase with genetic distance; and that genetic divergence predicts the strength of behavioural responses to playback, after removing the effects of acoustic similarity between subjects’ songs and playback stimuli. Collectively, these results demonstrate that the most distantly related species have the most divergent songs; that male wrens perceive divergence in fine structural characteristics of songs; and that perceptual differences between species reflect evolutionary history. This study offers novel insight into the importance of acoustic divergence of learned signals and receiver responses in species recognition.     

Luminescence experiments involved in the mechanism of streptozotocin diabetes and cataract formation

Streptozotocin (STZ)‐induced diabetes is linked to excessive nitric oxide (NO), and possibly peroxynitrite (OONO^–) and/or other nitrogen oxides, e.g. nitrogen trioxide (N₂O₃), which damages DNA of pancreatic β cells, causing death and loss of insulin. Simultaneous injection of carboxy‐PTIO (CPTIO) and STZ prevents diabetes and cataract formation in rats, whereas 4‐hydroxy‐Tempo (4HT) does not. CPTIO oxidizes nitric oxide to nitrite, which prevents production of the diabetogenic toxin. Peroxynitrite may not be involved, since 4HT (converts O₂^– to H₂O₂) injected with STZ produces diabetes. All six of the control rats injected with STZ became diabetic and developed cataracts after 3 months. Eight rats injected with STZ and CPTIO were non‐diabetic with no cataracts up to a year. This work establishes the idea that excessive nitric oxide is a primary initiator in STZ diabetes. Luminescence experiments using OONO^– generation from SIN‐1 with L‐012 indicates that 4HT is an effective inhibitor, while CPTIO is ineffective. Experiments with dilute solutions of nitrogen trioxide added to ladder or plasmid DNA reveal extensive nicking of DNA, thereby raising the possibility that other oxides of nitrogen could be involved with the damage to DNA. It can be concluded that diabetes can be prevented by oxidizing excessive NO from STZ. Copyright © 2008 John Wiley & Sons, Ltd.     

Spontaneously ruptured gastrointestinal stromal tumor (GIST) of the jejunum mimicking acute appendicitis

Gastrointestinal stromal tumors (GISTs) are characterized with diverse clinical presentations, including acute and chronic gastrointestinal bleeding, abdominal pain, presence of an intra-abdominal mass, anorexia, and intestinal obstruction. A 60-year-old obese woman presented as an acute abdominal emergency with right lower quadrant (RLQ) pain and tenderness, nausea and leukocytosis, all mimicking acute appendicitis. Laparotomy revealed a spontaneously ruptured GIST of the jejunum, which was localized to the RLQ due to postoperative adhesions following previous two cesarean sections and cholecystectomy. Complete surgical resection was performed, followed by an uneventful early postoperative course.     

Multiple periglacial refugia in the Patagonian steppe and post‐glacial colonization of the Andes: the phylogeography of Calceolaria polyrhiza

Aim We perform a phylogeographical study of an endemic Patagonian herbaceous plant to assess whether geographical patterns of genetic variation correspond to in situ Pleistocene survival or to glacial retreat and post‐glacial expansion. We also seek to determine the locations of potential glacial refugia and post‐glacial colonization routes. Location Southern Andes and Patagonian steppe. Methods We used Calceolaria polyrhiza, a widely distributed Patagonian herbaceous plant that occurs mainly in the understorey of Nothofagus rain forests and in the arid Patagonian steppe, as our model system. The chloroplast intergenic spacer trnH–psbA was sequenced for 590 individuals from 68 populations. Sequence data were analysed using phylogenetic (maximum parsimony, maximum likelihood and Bayesian inference) and population genetic (spatial analyses of molecular variance, mismatch distributions and neutrality tests) methods. Nested clade phylogeographic analyses, and divergence time estimates using a calibrated molecular clock, were also conducted. Results A total of 27 haplotypes identified in the present study clustered into four primary genealogical lineages, revealing three significant latitudinal phylogeographical breaks. The two high Andean lineages probably split first, during the late Miocene, and the Patagonian lineage split around 4 Ma, coincident with the establishment of the Patagonian steppe. Within each haplogroup, major diversification occurred in the Pleistocene. The Patagonian groups show a pattern consistent with a rapid post‐glacial expansion and colonization of the Andean flanks, achieved independently by four lineages. The highest haplotype diversity was found along a longitudinal transect that is remarkably congruent with the limit of the ice‐sheet extension during the Greatest Patagonian Glaciation. A north‐east expansion is evident, which is probably associated with the ‘Arid Diagonal’ fluctuations. Main conclusions Glacial climate fluctuations had a substantial impact on the diversification, distribution and demography of the study species. A scenario of multiple periglacial Pleistocene refugia and subsequent multiple recolonization routes, from eastern Patagonia to the Andean flanks, may explain the phylogeographical patterns observed. However, current genetic structure also preserves the imprints of older events that probably occurred in the Miocene and Pliocene, providing evidence that multiple processes, operating at different spatial and temporal scales, have moulded biodiversity in Patagonia.     

Effects of social support during parturition on maternal and infant morbidity.

Because continuous social support during labour is a component of care in many societies but inconsistent in our own, the clinical effect of support during labour on maternal and neonatal morbidity were studied. Social support was provided by female companions. Four hundred and sixty five healthy primigravidous women were enrolled using a randomised design. Compared with 249 women undergoing labour alone 168 women who had supportive female companions throughout labour had significantly fewer perinatal complications (p less than 0.001), including caesarean sections (7% v 17%, p less than 0.01) and oxytocin augmentation (2% v 13%, p less than 0.001), and fewer infants admitted to neonatal intensive care (p less than 0.10). Of the women who had an uncomplicated labour and delivery requiring no interventions, those with a companion had a significantly shorter duration of labour (7.7 hours v 15.5 hours, p less than 0.001). This study suggests that constant human support may be of great benefit to women during labour.     

Molecular evidence for the origin and evolutionary history of the rare American desert monotypic family Setchellanthaceae

Setchellanthus caeruleus, which has disjunct populations in the north of the Chihuahuan Desert and in the Tehuacán-Cuicatlán valley, was selected to understand the evolutionary history of plants in this desert and its southerly relicts. This species constitutes the monotypic family Setchellanthaceae, which forms part of a group of plants that produce mustard-oil glucosides or glucosinolates. Molecular phylogenetic analyses based on DNA plastid sequences of plants of S. caeruleus from both areas, including representative taxa of the order Brassicales, were carried out to estimate the time of origin of the family (based on matK?+?rcbL) and divergence of populations (based on psbI-K, trnh-psbA, trnL-trnF). In addition, comparative ecological niche modelling was performed to detect if climate variables vary significantly in northern and southern populations. Analyses revealed that Setchellanthaceae is an ancient lineage that originated between 78 and 112 Mya during the mid-late Cretaceous—much earlier than the formation of the Chihuahuan Desert. The molecular data matrix displayed a few indel events as the only differences of plastid DNA sequences between northern and southern populations. It is suggested that due to climate changes in this desert in the Pliocene, populations of Setchellanthus remained in the Sierra de Jimulco and in Cuicatlán, in climatically stable locations. Ecological niche models of northern populations predict niches of southern populations and identity niche tests indicate that there are no differences in their ecological niches.     

Training a new response using conditioned reinforcement

Some of the most frequently used methods in the study of conditioned reinforcement seem to be insufficient to demonstrate the effect. The clearest way to assess this phenomenon is the training of a new response. In the present study, rats were exposed to a situation in which a primary reinforcer and an arbitrary stimulus were paired and subsequently the effect of this arbitrary event was assessed by presenting it following a new response. Subjects under these conditions emitted more responses compared to their own responding before the pairing and to their responding on a similar operandum that was available concurrently that had no programmed consequences. Response rates also were higher compared to responding by subjects in similar conditions in which there was no contingency (a) between the arbitrary stimulus and the reinforcer, (b) between the response and the arbitrary stimulus or (c) both. Results are discussed in terms of necessary and sufficient conditions to study conditioned reinforcement.