An Ornithopod-Dominated Tracksite from the Lower Cretaceous Jiaguan Formation (Barremian–Albian) of Qijiang,South-Central China: New Discoveries,Ichnotaxonomy, Preservation and Palaeoecology

The historically-famous Lotus Fortress site, a deep 1.5–3.0-meter-high, 200-meter-long horizonal notch high up in near-vertical sandstone cliffs comprising the Cretaceous Jiaguan Formation, has been known since the 13th Century as an impregnable defensive position. The site is also extraordinary for having multiple tetrapod track-bearing levels, of which the lower two form the floor of part of the notch, and yield very well preserved asseamblages of ornithopod, bird (avian theropod) and pterosaur tracks. Trackway counts indicate that ornithopods dominate (69%) accounting for at least 165 trackmakers, followed by bird (18%), sauropod (10%), and pterosaur (3%). Previous studies designated Lotus Fortress as the type locality of Caririchnium lotus and Wupus agilis both of which are recognized here as valid ichnotaxa. On the basis of multiple parallel trackways both are interpreted as representing the trackways of gregarious species. C. lotus is redescribed here in detail and interpreted to indicate two age cohorts representing subadults that were sometimes bipedal and larger quadrupedal adults. Two other previously described dinosaurian ichnospecies, are here reinterpreted as underprints and considered nomina dubia. Like a growing number of significant tetrapod tracksites in China the Lotus Fortress site reveals new information about the composition of tetrapod faunas from formations in which the skeletal record is sparse. In particular, the site shows the relatively high abundance of Caririchium in a region where saurischian ichnofaunas are often dominant. It is also the only site known to have yielded Wupus agilis. In combination with information from other tracksites from the Jiaguan formation and other Cretaceous formations in the region, the track record is proving increasingly impotant as a major source of information on the vertebrate faunas of the region. The Lotus Fortress site has been developed as a spectacular, geologically-, paleontologically- and a culturally-significant destination within Qijiang National Geological Park.     

Starch turnover in shoot-forming tobacco callus

Tobacco callus grown under shoot-forming conditions or in the presence of gibberellic acid, which inhibits shoot formation, was incubated in [¹⁴C]-sucrose at three different periods in culture and then replanted. Evolution of ¹⁴CO₂ occurred during the 10 day post-incubation period. Most of the radioactivity was incorporated into the ethanol-soluble fraction, which lost most of its label after 24 h. Starch was the major ethanol-insoluble component and post-incubation synthesis occurred in this fraction for 24 h or longer. Greater net synthesis of starch occurred in shoot-forming tissue and the loss of label from starch began later than in tissue cultured in the presence of gibbe-rellic acid. Newly synthesized starch was not immediately utilised in the organogenic process, but its utilization could be correlated with the shoot-forming process.     

The observed range for temporal mean-variance scaling exponents can be explained by reproductive correlation

The mean-variance scaling relationship known as Taylor's power law has been well documented empirically over the past four decades but a general theoretical explanation for the phenomenon does not exist. Here we provide an explanation that relates empirical patterns of temporal mean-variance scaling to individual level reproductive behavior. Initially, we review the scaling behavior of population growth models to establish theoretical limits for the scaling exponent b that is in agreement with the empirically observed range (1≤b≤2). We go on to show that the degree of reproductive covariance among individuals determines the scaling exponent b. Independent reproduction results in an exponent of one, while completely correlated reproduction results in the upper limit of two. Intermediate exponents, which are common empirically, can be generated through the decay of reproductive covariance with increasing population size. Finally, we describe how the link between reproductive correlation and the scaling exponent provides a way to infer properties of individual-level reproductive behavior, such as the relative influence of demographic stochasticity, from a macroecological pattern.     

Phosphorylation of Synaptic GTPase-activating Protein (synGAP) by Ca2+/Calmodulin-dependent Protein Kinase II (CaMKII) and Cyclin-dependent Kinase 5 (CDK5) Alters the Ratio of Its GAP Activity toward Ras and Rap GTPases

synGAP is a neuron-specific Ras and Rap GTPase-activating protein (GAP) found in high concentrations in the postsynaptic density (PSD) fraction from the mammalian forebrain. We have previously shown that, in situ in the PSD fraction or in recombinant form in Sf9 cell membranes, synGAP is phosphorylated by Ca²⁺/calmodulin-dependent protein kinase II (CaMKII), another prominent component of the PSD. Here, we show that recombinant synGAP (r-synGAP), lacking 102 residues at the N terminus, can be purified in soluble form and is phosphorylated by cyclin-dependent kinase 5 (CDK5) as well as by CaMKII. Phosphorylation of r-synGAP by CaMKII increases its HRas GAP activity by 25% and its Rap1 GAP activity by 76%. Conversely, phosphorylation by CDK5 increases r-synGAP''s HRas GAP activity by 98% and its Rap1 GAP activity by 20%. Thus, phosphorylation by both kinases increases synGAP activity; CaMKII shifts the relative GAP activity toward inactivation of Rap1, and CDK5 shifts the relative activity toward inactivation of HRas. GAP activity toward Rap2 is not altered by phosphorylation by either kinase. CDK5 phosphorylates synGAP primarily at two sites, Ser-773 and Ser-802. Phosphorylation at Ser-773 inhibits r-synGAP activity, and phosphorylation at Ser-802 increases it. However, the net effect of concurrent phosphorylation of both sites, Ser-773 and Ser-802, is an increase in GAP activity. synGAP is phosphorylated at Ser-773 and Ser-802 in the PSD fraction, and its phosphorylation by CDK5 and CaMKII is differentially regulated by activation of NMDA-type glutamate receptors in cultured neurons.     

Novel observations of midge and mosquito larval population dynamics in leaves of the northern pitcher plant,Sarracenia purpurea L.

The invertebrate communities in Sarracenia purpurea were characterized by surveying the contents of 474 leaves from six pitcher plant populations in the eastern United States. More than 8200 invertebrate specimens, both living and dead, were recovered. Midge and mosquito larvae comprised 7907 (96%) of the specimens, with a mean of 16.9 dipteran larvae per leaf. Although midge larvae were present at all collection sites, mosquito larvae were absent from two of the sites. In the latter sites, the number of midge larvae per leaf was greater. This report documents for the first time that there is no statistical difference between the average number of Diptera larvae per leaf for sites that contain both midge and mosquito larvae compared to sites that contain only midge larvae. It appears that pitcher plants maintain an average number of larvae per leaf based on a number of interacting factors which we do not fully understand. This investigation documents that in the absence of mosquito larvae, more midge larvae are found per leaf per leaf than would be predicted based on data from sites that contain both larval taxa.     

Regulatory mechanisms of biosynthesis of betacyanin and anthocyanin in relation to cell division activity in suspension cultures

Regulatory mechanisms of betacyanin biosynthesis in suspension cultures of Phytolacca americana and anthocyanin in Vitis sp. were investigated in relation to cell division activity.Betacyanin biosynthesis in Phytolacca cells clearly shows a positive correlation with cell division, as the peak of betacyanin accumulation was observed at the log phase of batch cultures. Incorporation of radioactivity from labelled tyrosine into betacyanin also showed a peak at early log phase. Aphidicolin, an inhibitor of DNA synthesis, and propyzamide, an antimicrotubule drug, reduced betacyanin accumulation and inhibited the incorporation of radioactivity from labelled tyrosine into betacyanin at concentrations which were inhibitory to cell division. Both inhibitors reduced the incorporation of radioactivity from labelled tyrosine to 3,4-dihydroxyphenylalanine (DOPA), but the incorporation of labelled DOPA into betacyanin was not affected. These results suggest that the conversion of tyrosine to DOPA is coupled with cell division activity.In contrast, the anthocyanin accumulation in Vitis cells showed a negative correlation with cell division. Accumulation occurred at the stationary phase in batch cultures when cell division ceased. Aphidicolin or reduced phosphate concentration induced a substantial increase in anthocyanin accumulation as well as the inhibition of cell division. Chalcone synthase (CHS) activity increased at the time of anthocyanin accumulation. Northern blotting analysis indicated that changes in CHS mRNA levels corresponded to similar changes in enzymatic activity. The pool size of endogenous phenylalanine was low during active cell division, but increased before anthocyanin began to accumulate and concomitantly with increasing levels of CHS mRNA. Exogenous supply of phenylalanine at the time of low endogenous levels induced the elevation of CHS mRNA and anthocyanin accumulation. These results indicate that the elevation of endogenous phenylalanine levels, when cell division ceases, may cause the increase in CHS mRNA levels, resulting in increased CHS activity and subsequently in anthocyanin accumulation in Vitis suspension cultures.Abbreviations CHS chalcone synthase - CHFI chalcone flavanone isomerase - DOPA 3,4-dihydroxyphenylalanine - PAL phenylalanine ammonia lyase     

Non-Human Primates Harbor Diverse Mammalian and Avian Astroviruses Including Those Associated with Human Infections

Astroviruses (AstVs) are positive sense, single-stranded RNA viruses transmitted to a wide range of hosts via the fecal-oral route. The number of AstV-infected animal hosts has rapidly expanded in recent years with many more likely to be discovered because of the advances in viral surveillance and next generation sequencing. Yet no study to date has identified human AstV genotypes in animals, although diverse AstV genotypes similar to animal-origin viruses have been found in children with diarrhea and in one instance of encephalitis. Here we provide important new evidence that non-human primates (NHP) can harbor a wide variety of mammalian and avian AstV genotypes, including those only associated with human infection. Serological analyses confirmed that >25% of the NHP tested had antibodies to human AstVs. Further, we identified a recombinant AstV with parental relationships to known human AstVs. Phylogenetic analysis suggests AstVs in NHP are on average evolutionarily much closer to AstVs from other animals than are AstVs from bats, a frequently proposed reservoir. Our studies not only demonstrate that human astroviruses can be detected in NHP but also suggest that NHP are unique in their ability to support diverse AstV genotypes, further challenging the paradigm that astrovirus infection is species-specific.