Nerves containing substance P,vasoactive intestinal polypeptide,enkephalin or somatostatin in the guinea-pig taenia coli

Summary The guinea-pig taenia coli is rich in peptide-containing nerves. Nerve fibres containing substance P (SP), vasoactive intestinal peptide (VIP), or enkephalin, were numerous in the smooth muscle while somatostatin fibres were very few. Nerve fibres displaying SP or VIP immunoreactivity were numerous in the myenteric plexus. Enkephalin nerve fibres were fairly numerous in the plexus while somatostatin nerve fibres were sparse. Nerve cell bodies containing immunoreactive SP or VIP were regularly seen in the plexus. Delicate varicose elements of the different types of nerve fibres were found to ramify around nerve cell bodies in a manner suggestive of innervation.In the electron microscope the various peptide-storing nerve fibres (i.e., elements containing SP, VIP or enkephalin) were found to contain a varying number of fairly large, electron-opaque vesicles in the varicose swellings. These vesicles represent the storage site of the neuropeptides.The isolated taenia coli responded to electrical nerve stimulation with a contraction. After cholinergic and adrenergic blockade the contractile response was replaced by a relaxation followed by a contraction upon cessation of stimulation. SP contracted the taenia while VIP caused a relaxation. The enkephalins raised the resting tension slightly while somatostatin had no effect. These observations are compatible with a role for SP as an excitatory neurotransmitter and for VIP as an inhibitory one, and with the view that both SP neurones and VIP neurones act as motor neurones. In preparations contracted by SP the electrically induced contractions were reduced in amplitude while the electrically induced relaxations seen after adrenergic and cholinergic blockade were enhanced in amplitude. In preparations relaxed by VIP there was an increased contractile response to electrical stimulation, while in the atropine + guanethidine-treated preparation the electrically induce relaxations were reduced in amplitude. The enkephalins reduced the contractile response to electrical stimulation, while somatostatin induced a very small reduction in the amplitude of such responses. These observations suggest that SP neurones and VIP neurones may play additional roles as interneurones. Somatostatin neurones probably act as interneurones. Enkephalin-containing fibres may serve to modify the release of transmitter from other nerves in the smooth muscle, perhaps through axo-axonal arrangements. Alternatively, the enkephalin nerve fibres in the smooth muscle are afferent elements involved in mediating sensory impulses to the myenteric plexus.     

Fine Tuning Inflammation at the Front Door: Macrophage Complement Receptor 3-mediates Phagocytosis and Immune Suppression for Francisella tularensis

Complement receptor 3 (CR3, CD11b/CD18) is a major macrophage phagocytic receptor. The biochemical pathways through which CR3 regulates immunologic responses have not been fully characterized. Francisella tularensis is a remarkably infectious, facultative intracellular pathogen of macrophages that causes tularemia. Early evasion of the host immune response contributes to the virulence of F. tularensis and CR3 is an important receptor for its phagocytosis. Here we confirm that efficient attachment and uptake of the highly virulent Type A F. tularensis spp. tularensis strain Schu S4 by human monocyte-derived macrophages (hMDMs) requires complement C3 opsonization and CR3. However, despite a>40-fold increase in uptake following C3 opsonization, Schu S4 induces limited pro-inflammatory cytokine production compared with non-opsonized Schu S4 and the low virulent F. novicida. This suggests that engagement of CR3 by opsonized Schu S4 contributes specifically to the immune suppression during and shortly following phagocytosis which we demonstrate by CD11b siRNA knockdown in hMDMs. This immune suppression is concomitant with early inhibition of ERK1/2, p38 MAPK and NF-κB activation. Furthermore, TLR2 siRNA knockdown shows that pro-inflammatory cytokine production and MAPK activation in response to non-opsonized Schu S4 depends on TLR2 signaling providing evidence that CR3-TLR2 crosstalk mediates immune suppression for opsonized Schu S4. Deletion of the CD11b cytoplasmic tail reverses the CR3-mediated decrease in ERK and p38 activation during opsonized Schu-S4 infection. The CR3-mediated signaling pathway involved in this immune suppression includes Lyn kinase and Akt activation, and increased MKP-1, which limits TLR2-mediated pro-inflammatory responses. These data indicate that while the highly virulent F. tularensis uses CR3 for efficient uptake, optimal engagement of this receptor down-regulates TLR2-dependent pro-inflammatory responses by inhibiting MAPK activation through outside-in signaling. CR3-linked immune suppression is an important mechanism involved in the pathogenesis of F. tularensis infection.     

Testosterone Levels Are Negatively Associated with Childlessness in Males,but Positively Related to Offspring Count in Fathers

Variation in testosterone (T) is thought to affect the allocation of effort between reproductive and parenting strategies. Here, using a large sample of elderly American men (n = 754) and women (n = 669) we examined the relationship between T and self-reported parenthood, as well as the relationship between T and number of reported children. Results supported previous findings from the literature, showing that fathers had lower T levels than men who report no children. Furthermore, we found that among fathers T levels were positively associated with the number of children a man reports close to the end of his lifespan. Results were maintained when controlling for a number of relevant factors such as time of T sampling, participant age, educational attainment, BMI, marital status and reported number of sex partners. In contrast, T was not associated with either motherhood or the number of children women had, suggesting that, at least in this sample, T does not influence the allocation of effort between reproductive and parenting strategies among women. Findings from this study contribute to the growing body of literature suggesting that, among men, pair bonding and paternal care are associated with lower T levels, while searching and acquiring sex partners is associated with higher T levels.     

Morphology and Molecular Phylogeny of a New Marine,Sand-dwelling Dinoflagellate Genus,Pachena (Dinophyceae), with Descriptions of Three New Species

Marine benthic dinoflagellates are interesting not only because some epiphytic genera can cause harmful algal blooms but also for understanding dinoflagellate evolution and diversification. Our understanding of their biodiversity is far from complete, and many thecate genera have unusual tabulation patterns that are difficult to relate to the diverse known phytoplankton taxa. A new sand-dwelling genus, Pachena gen. nov., is described based on morphological and DNA sequence data. Three species were discovered in distant locations and are circumscribed, namely, P. leibnizii sp. nov. from Canada, P. abriliae sp. nov. from Spain, and P. meriddae sp. nov. from Italy. All species are tiny (about 9–23 μm long) and heterotrophic. Species are characterized by their tabulation (APC 4′ 3a 6′′ 5c 5s 5′′′ 2′′′′), an apical hook covering the apical pore, an ascending cingulum, and a sulcus with central list. The first anterior intercalary plate is uniquely “sandwiched” between two plates. The species share these features and differ in the relative sizes and arrangements of their plates, especially on the epitheca. The ornamentation of thecal plates is species-specific. The new molecular phylogenies based on SSU and LSU rDNA sequences contribute to understanding the evolution of the planktonic relatives of Pachena, the Thoracosphaeraceae.     

Abstracts of papers read at the Winter Meeting, 1961

Herdmania litoralis is a heterotrophic, sand-dwelling dinoflagellate with morphological characters that do not provide clear evidence for its systematic position in any existing family of dinoflagellates. Protoperidinium minutum is a heterotrophic, planktonic species that has a typical tabulation for the genus Protoperidinium. In order to infer the phylogenetic positions of these two species more confidently, we characterized the thecal plate patterns and determined small-subunit and large-subunit ribosomal DNA sequences (SSU rDNA and LSU rDNA, respectively) from both species. Intraindividual and intraspecific diversity of SSU and LSU rDNA data were characterized in H. litoralis using a combination of single-cell PCR approaches and analyses of PCR clones derived from multi-cell DNA extractions. The results of the molecular phylogenetic analyses demonstrated a novel, well-supported clade comprising both sand-dwelling species (H. litoralis and Thecadinium dragescoi) and planktonic species (P. minutum). Because the establishment of this clade also demonstrated that P. minutum is not a member of Protoperidinium, we reinstated and emended the genus Archaeperidinium Jörgensen 1912 Jörgensen, E. 1912. Bericht über die von der schwedischen hydrographisch-biologischen Kommission in den schwedischen Gewässern in den Jahren 1909–10 eingesammelten Planktonproben. Svenska Hydrograph.-Biol. Komm. Skr., 4: 1–20.  [Google Scholar].     

Leveraging plant hydraulics to yield predictive and dynamic plant leaf allocation in vegetation models with climate change

Plant functional traits provide a link in process‐based vegetation models between plant‐level physiology and ecosystem‐level responses. Recent advances in physiological understanding and computational efficiency have allowed for the incorporation of plant hydraulic processes in large‐scale vegetation models. However, a more mechanistic representation of water limitation that determines ecosystem responses to plant water stress necessitates a re‐evaluation of trait‐based constraints for plant carbon allocation, particularly allocation to leaf area. In this review, we examine model representations of plant allocation to leaves, which is often empirically set by plant functional type‐specific allometric relationships. We analyze the evolution of the representation of leaf allocation in models of different scales and complexities. We show the impacts of leaf allocation strategy on plant carbon uptake in the context of recent advancements in modeling hydraulic processes. Finally, we posit that deriving allometry from first principles using mechanistic hydraulic processes is possible and should become standard practice, rather than using prescribed allometries. The representation of allocation as an emergent property of scarce resource constraints is likely to be critical to representing how global change processes impact future ecosystem dynamics and carbon fluxes and may reduce the number of poorly constrained parameters in vegetation models.     

Validation of a universal set of primers to study animal-associated microeukaryotic communities

The application of metabarcoding to study animal-associated microeukaryotes has been restricted because the universal barcode used to study microeukaryotic ecology and distribution in the environment, the Small Subunit of the Ribosomal RNA gene (18S rRNA), is also present in the host. As a result, when host-associated microbial eukaryotes are analysed by metabarcoding, the reads tend to be dominated by host sequences. We have done an in silico validation against the SILVA 18S rRNA database of a non-metazoan primer set (primers that are biased against the metazoan 18S rRNA) that recovers only 2.6% of all the metazoan sequences, while recovering most of the other eukaryotes (80.4%). Among metazoans, the non-metazoan primers are predicted to amplify 74% of Porifera sequences, 4% of Ctenophora, and 15% of Cnidaria, while amplifying almost no sequences within Bilateria. In vivo, these non-metazoan primers reduce significantly the animal signal from coral and human samples, and when compared against universal primers provide at worst a 2-fold decrease in the number of metazoan reads and at best a 2800-fold decrease. This easy, inexpensive, and near-universal method for the study of animal-associated microeukaryotes diversity will contribute to a better understanding of the microbiome.     

Dynamic investigation and modeling of the nitrogen cometabolism in Methylococcus capsulatus ( Bath)

The methanotrophic bacterium Methylococcus capsulatus is capable of assimilating methane and oxygen into protein-rich biomass, however, the diverse metabolism of the microorganism also allows for several undesired cometabolic side-reactions to occur. In this study, the ammonia cometabolism in Methylococcus capsulatus is investigated using pulse experiments. Surprisingly Methylococcus capsulatus oxidizes ammonia to nitrate through a yet unknown mechanism and fixes molecular nitrogen even at a high dissolved oxygen tension. The observed phenomena can be modeled using 14 ordinary differential equations and 18 kinetic parameters, of which 6 were revealed by Morris screening to be identifiable from the experimental data. Monte Carlo simulations showed that the model was robust and accurate even with uncertainty in the parameter values as confirmed by statistical error analysis.     

Monocytes recruited into the alveolar air space of mice show a monocytic phenotype but upregulate CD14

The DeltaF508 cystic fibrosis transmembrane conductance regulator (CFTR) is a temperature-sensitive trafficking mutant that is detected as an immature 160-kDa form (band B) in gel electrophoresis. The goal of this study was to test the hypothesis that HSP70, a member of the 70-kDa heat shock protein family, promotes DeltaF508 CFTR processing to the mature 180-kDa form (band C). Both pharmacological and genetic techniques were used to induce HSP70. IB3-1 cells were treated with sodium 4-phenylbutyrate (4PBA) to promote maturation of DeltaF508 CFTR to band C. A dose-dependent increase in band C and total cellular HSP70 was observed. Under these conditions, HSP70-CFTR complexes were increased and 70-kDa heat shock cognate protein-CFTR complexes were decreased. Increased DeltaF508 CFTR maturation was also seen after transfection with an HSP70 expression plasmid and exposure to glutamine, an inducer of HSP70. With immunofluorescence techniques, the increased appearance of CFTR band C correlated with CFTR distribution beyond the perinuclear regions. These data suggest that induction of HSP70 promotes DeltaF508 CFTR maturation and trafficking.     

Conebulization of surfactant and urokinase restores gas exchange in perfused lungs with alveolar fibrin formation

Alveolar fibrin generation has been suggested to possess strong surfactant-inhibitory potency. In perfused rabbit lungs, fibrin formation in the alveolar space was induced by sequential ultrasonic aerosolization of fibrinogen and thrombin, and the efficacy of rescue administration of surfactant and urokinase was investigated. Ventilation-perfusion (VA/Q) distribution was assessed by the multiple inert gas elimination technique. Aerosolization of fibrinogen (approximately 20 mg/kg body wt) increased shunt flow to approximately 7%. Sequential nebulization of fibrinogen and thrombin (1.3 U/kg body wt) caused alveolar fibrin deposition, documented immunohistologically, and provoked marked shunt flow, progressing to approximately 22% at the end of the experiments. The hemodynamics were virtually unchanged. Rescue aerosolization of natural bovine surfactant (15 mg/kg body wt) or urokinase-type plasminogen activator (4,500 U/kg body wt), undertaken after fibrin formation, improved gas exchange but progressive shunt flow still occurred (efficacy, surfactant > urokinase). In contrast, conebulization of surfactant and urokinase reversed shunt flow to approximately 7%, with an increased appearance of normal VA/Q matching. We conclude that alveolar fibrin formation is a potent surfactant-inhibitory mechanism in intact lungs, provoking severe VA/Q mismatch with a predominance of shunt flow, and that rescue aerosolization of surfactant plus urokinase may offer restoration of gas exchange under these conditions.