GRIESBACHIAN AND DIENERIAN (EARLY TRIASSIC) AMMONOID FAUNAS FROM NORTHWESTERN GUANGXI AND SOUTHERN GUIZHOU (SOUTH CHINA)

Abstract: Intensive sampling of the Luolou (northwestern Guangxi) and the Daye (southern Guizhou) Formations in South China leads to the recognition of a regional Griesbachian and Dienerian ammonoid succession for this key palaeobiogeographical area. The new biostratigraphical sequence comprises the upper Griesbachian ‘Ophiceras beds’ and the lower Dienerian ‘Proptychites candidus beds’, which are separated from the uppermost Dienerian ‘Clypites beds’ by an unfossiliferous interval. These faunas contain some taxa with wide geographic distribution (e.g. Ambites, Pleurambites, Pleurogyronites, Proptychites candidus), thus facilitating correlation with faunal successions from other regions (i.e. British Columbia, Canadian Arctic, Himalayas and South Primorye). Two new genera (Jieshaniceras and Shangganites) and three new species (Anotoceras subtabulatus, Pleurambites radiatus and Shangganites shangganense) are described.     

Tuning in to multiple predators: conflicting demands for shell morphology in a freshwater snail

1. We examined the response to chemical cues from fish and crayfish, two predators with contrasting feeding modes, and their single and combined effect on shell morphology in the freshwater snail Radix balthica. 2. Snails were subjected to four treatments: tench (Tinca tinca), signal crayfish (Pacifastacus leniusculus), a combination of tench and signal crayfish and no predators (control). Shell shape, crushing resistance and shell thickness were quantified. We also analysed whether shape or shell thickness contributes most to crushing resistance. 3. Chemical cues from the fish induced a rounder shell shape in R. balthica, a thicker shell and a higher crushing resistance, whereas crayfish chemical cues had no effect on shell morphology, shell thickness or crushing resistance. Shell shape contributed more to crushing resistance than shell thickness. 4. The combined predator treatment showed an intermediate response between the fish and crayfish treatments. Shell roundness was reduced compared with the fish treatment, but the reduced crushing resistance that comes with a less rounded shell was compensated by an increased investment in extra shell material, exceeding that of the fish treatment. 5. Our study extends previous studies of multipredator effects on phenotypically plastic freshwater snails by showing that the snails are able to fine‐tune different elements of morphology to counter predator‐specific foraging modes.     

The Elusive Honey Bee Dance “Language” Hypothesis

In the mid-1930s, Karl von Frisch proposed the equivalent of an odor-search hypothesis for honey bee recruitment to food sources. A decade later he switched to the equivalent of a dance language hypothesis (though he apparently did not consider his conclusions as hypotheses in either case). The later and more exotic hypothesis rapidly gained acceptance, but it failed its first experimental tests in the mid-1960s; searching recruits did not behave as von Frisch indicated they should under the language hypothesis. His earlier and more conservative odor-search hypothesis meshed better with results obtained in those test experiments. Language advocates then ignored basic precepts of scientific process, rejected and/or ignored results not in accord with their favored hypothesis, and instead repeatedly sought additional supportive evidence. While so doing, they inadvertently accumulated yet more evidence counter to von Frisch's original intent. By invoking ad hoc modifications and qualifications, advocates weakened, rather than strengthened, the hypothesis they continued to embrace. That strict adherence to the language hypothesis has had an unfortunate result; the exclusive investment in that line of research by various governmental agencies has failed to provide practical help to beekeepers or growers in the past half-century.     

Proteomic analysis of human ventricular cerebrospinal fluid from neurologically normal, elderly subjects using two-dimensional LC-MS/MS

A two-dimensional liquid chromatography separation scheme coupled to tandem mass spectrometry (2-D LC-MS/MS) was utilized to profile the proteome of human CSF. Ventricular CSF samples acquired post-mortem from 10 cognitively normal elderly subjects (mean +/- SEM Braak stage = 1.7 +/- 0.2) were analyzed to determine their protein composition. Raw CSF samples were subjected to an immunobased processing method to remove highly abundant albumin and immunoglobulin (Ig), allowing better detection of lower-abundance proteins. Samples were subjected to trypsin proteolysis followed by C18 solid-phase extraction. Tryptic CSF peptides were separated using a 2-D LC column, in which both strong cation exchange (SCX) and C18 phases were packed into a single capillary. MS/MS spectra of CSF peptides were searched against a human sub-database of the NBCI nonredundant database using the SEQUEST algorithm. Search results were further filtered using DTAselect, and individual samples were compared to one another using Contrast. Using this method, we were able to unambiguously identify 249 CSF proteins from 10 subjects. Of these proteins, 38% were unique to individual subjects, whereas only 6% were common to all 10 subjects. These results suggest considerable subject-to-subject variability in the CSF proteome.     

Perturbation of EGF-activated MEK1 and PKB signal pathways by TGF-beta1 correlates with perturbation of EGF-induced cyclin D1 and DNA synthesis by TGF-beta1 in C3H 10T1/2 cells

In mouse C3H 10T1/2 cells, we previously reported that TGF-beta1 first delays and later potentiates EGF-induced DNA synthesis corresponding to an inhibition of EGF-induced cyclin D1 expression at t = 13 h. We report here that in accord with DNA synthesis kinetics, TGF-beta1 initially suppresses EGF-induced cyclin D1 expression then later releases the inhibition. Furthermore, TGF-beta1 also first decreases and later potentiates the levels of EGF-activated MEK1/MAPK and PKB, indicating the existence of cross talk between TGF-beta 1- and EGF-activated signal transduction pathways. PD98059, the specific inhibitor of MEK1, significantly blocks EGF-induced DNA synthesis, whereas wortmannin, the PI3K inhibitor, exerts a modest inhibitory effect, which suggests that the activation of MEK1-MAPK pathway plays a major role in EGF-induced DNA synthesis and the activation of PI3K-PKB pathway plays a minor role. Upon examination of mechanisms underlying the cross talk, it was discovered that application of TGF-beta1 triggers a rapid association between Raf-1 and catalytic subunits of PKA, which are reported to be able to inactivate Raf-1 upon activation. Therefore, TGF-beta1 may activate PKA to inhibit the EGF-activated MEK1-MAPK pathway. The wortmannin-sensitive phosphorylation at the thr(389) site is necessary for activation of p70s6K, an important kinase involved in mitogen-stimulated protein synthesis. Although we found that EGF-stimulated p70s6K phosphorylates through a MAPK-dependent and a MAPK-independent (wortmannin-sensitive) pathway, TGF-beta1 failed to block EGF-triggered phosphorylation of p70s6K at thr(389) and thr(421)/ser(424) sites, implying that PKB inhibition by TGF-beta1 may result from inhibition of PDK1 activity instead of inhibition of PI3K activity. These data also suggest that TGF-beta1 may selectively perturb certain EGF-activated MAPK pools.     

Induced systemic resistance responses in perennial ryegrass against Magnaporthe oryzae elicited by semi‐purified surfactin lipopeptides and live cells of Bacillus amyloliquefaciens

The suppressive ability of several strains of cyclic lipopeptide‐producing Bacillus rhizobacteria to grey leaf spot disease caused by Magnaporthe oryzae has been documented previously; however, the underlying mechanism(s) involved in the induced systemic resistance (ISR) activity in perennial ryegrass (Lolium perenne L.) remains unknown. Root‐drench application of solid‐phase extraction (SPE)‐enriched surfactin and live cells of mutant Bacillus amyloliquefaciens strain FZB42‐AK3 (produces surfactin, but not bacillomycin D and fengycin) significantly reduced disease incidence and severity on perennial ryegrass. The application of the treatments revealed a pronounced multilayered ISR defence response activation via timely and enhanced accumulation of hydrogen peroxide (H₂O₂), elevated cell wall/apoplastic peroxidase activity, and deposition of callose and phenolic/polyphenolic compounds underneath the fungal appressoria in naïve leaves, which was significantly more intense in treated plants than in mock‐treated controls. Moreover, a hypersensitive response (HR)‐type reaction and enhanced expression of LpPrx (Prx, peroxidase), LpOXO4 (OXO, oxalate oxidase), LpPAL (PAL, phenylalanine ammonia lyase), LpLOXa (LOX, lipoxygenase), LpTHb (putative defensin) and LpDEFa (DEFa, putative defensin) in perennial ryegrass were associated with SPE‐enriched surfactin and live AK3 cell treatments, acting as a second layer of defence when pre‐invasive defence responses failed. The results indicate that ISR activity following surfactin perception may sensitize H₂O₂‐mediated defence responses, thereby providing perennial ryegrass with enhanced protection against M. oryzae.     

The effect of phorbol esters on the proliferation of C3H-10T1/2 mouse fibroblasts: Consideration of both stimulatory and inhibitory effects

TPA stimulates cell cycle activation in both serum-deprived and density-inhibited cultures. The cells reestablish cycle arrest after no more than one generation, and addition of fresh drug produces no further response. However, cells freshly trypsinized can respond with a series of repetitive generations resulting in 3.5–4.0 population doublings over 72 hrs. In kinetic pulse experiments TPA enhanced ³H-thymidine incorporation in densityinhibited cells stimulated by fresh serum but only after markedly suppressing incorporation 8–13 hrs after serum stimulation. When cells arrested by serum deprivation were pretreated with TPA, fresh serum stimulation led to initiation of ³H-TdR incorporation 5 hrs earlier than untreated controls. However, TPA addition at the time of serum stimulation did not lead to a suppression at 8–13 hrs, whereas enhancement was observed during peak incorporation times regardless of whether the cells were pretreated with TPA during serum deprivation. The results support the concept that there can exist within G₁ multiple states of responsiveness to phorbol esters. These pharmacologically induced states may be correlated with corresponding physiological states of the G₁ phase of cell cycle.