A new readily processable polyimide

As part of an effort to develop tough solvent resistance thermoplastics for potential use as structural resins on aerospace vehicles, a new processable polyimide was evaluated. The synthesis involved the reaction of a new diamine, 1,3-bis 2-(3-aminophenoxy)ethyl ether, with 3,3',4,4'-benzophenonetetracarboxylic dianhydride to form the polyamic acid and subsequent conversion of it to the polyimide. Various physical properties such as thermal stability, solvent resistance, glass transition temperature, crystalline melt temperature, melt viscosity and mechanical properties such as fracture toughness, adhesive, film and composite properties are reported. Of particular interest is the extremely high titanium to titanium tensile shear strength obtained for this polyimide

Patterns of Mesophotic Benthic Community Structure on Banks Off vs Inside the Continental Shelf Edge, Gulf of Mexico

Information on the biodiversity and geographic patterns of mesophotic, sessile, epibenthic communities on banks around and at the edge of the continental shelf, northern Gulf of Mexico, has been limited. These communities vary in their environments and are prone to disturbance from Outer Continental Shelf oil- and gas-related activities and fishing (trawling and long-lining). We surveyed these communities on the flanks of 13 banks to determine species richness, species composition, similarities between benthic communities, and geographic patterns in community structure. We sampled to ≤ 181 m in depth via a remotely operated vehicle using a vertically mounted digital camera bearing two lasers for scale and a flash (generally 10 drop-sites/bank, 5 transects/drop-site, and ≤11 photos/transect). Data analysis via PATN revealed three main Bank Groups: the on-shelf group containing 29 Fathom and Sonnier Banks; an anomalous bank—Geyer Bank; and the shelf edge group—Horseshoe, 28 Fathom, Bright, Alderdice, Bouma, Rankin, Rezak, Elvers, McGrail, and Sidner Banks. Most species-rich banks (Bank Group 3) occurred at the shelf edge. Two of the species-poor banks (Bank Group 1) occurred further north, inside the shelf. Geyer Bank (Bank Group 2) occurred at the shelf edge but was anomalously species-poor. Box-and-whisker analyses identified four Species Groups driving the Bank Groupings. Species Group 4 (the Elatopathes abientina/Nicella sp. group) was the largest (also containing Peysonellia sp.), primarily defining Bank Group 3. Species Groups 2 (the Antipathes sp./Gorgonian G04 group) and 3 (low species abundances) were also associated with Bank Group 3. Species Group 4 (the Elatopathes abientina/Nicella sp. group) was a major contributor to Bank Group 2 (Geyer Bank). Species Group 2 (the Antipathes sp./Gorgonian G04 group) was the primary constituent of the on-shelf Bank Group 1, also characterized by low species richness. Most species had a comparative abundance of ≤20%. The high species richness and affinities exhibited by Bank Group 3 are likely due to continual exposure to warm, low-turbidity Caribbean water at the shelf edge. Banks inside the shelf likely vary from the others as a result of exposure to cooler winter temperatures and higher turbidity due to wind-forced inshore currents. The reasons for the unique community structure on Geyer Bank are as yet unknown. Shelf-edge banks tend to be more species rich than on-shelf banks

Adult Neurogenesis: Ultrastructure of a Neurogenic Niche and Neurovascular Relationships

The first-generation precursors producing adult-born neurons in the crayfish (Procambarus clarkii) brain reside in a specialized niche located on the ventral surface of the brain. In the present work, we have explored the organization and ultrastructure of this neurogenic niche, using light-level, confocal and electron microscopic approaches. Our goals were to define characteristics of the niche microenvironment, examine the morphological relationships between the niche and the vasculature and observe specializations at the boundary between the vascular cavity located centrally in the niche. Our results show that the niche is almost fully encapsulated by blood vessels, and that cells in the vasculature come into contact with the niche. This analysis also characterizes the ultrastructure of the cell types in the niche. The Type I niche cells are by far the most numerous, and are the only cell type present superficially in the most ventral cell layers of the niche. More dorsally, Type I cells are intermingled with Types II, III and IV cells, which are observed far less frequently. Type I cells have microvilli on their apical cell surfaces facing the vascular cavity, as well as junctional complexes between adjacent cells, suggesting a role in regulating transport from the blood into the niche cells. These studies demonstrate a close relationship between the neurogenic niche and vascular system in P. clarkii. Furthermore, the specializations of niche cells contacting the vascular cavity are also typical of the interface between the blood/cerebrospinal fluid (CSF)-brain barriers of vertebrates, including cells of the subventricular zone (SVZ) producing new olfactory interneurons in mammals. These data indicate that tissues involved in producing adult-born neurons in the crayfish brain use strategies that may reflect fundamental mechanisms preserved in an evolutionarily broad range of species, as proposed previously. The studies described here extend our understanding of neurovascular relationships in the brain of P. clarkii by characterizing the organization and ultrastructure of the neurogenic niche and associated vascular tissues

Acetylcholine turnover in an autoactive molluscan neuron

1. We have studied acetylcholine (ACh) turnover at the cholinergic synapse between an identified motoneuron, the salivary burster (SB), and the muscle cells of the salivary duct (SD) in the terrestrial mollusk Limax maximus.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44284/1/10571_2004_Article_BF00710939.pd

Sustained proliferation in cancer: mechanisms and novel therapeutic targets

Proliferation is an important part of cancer development and progression. This is manifest by altered expression and/or activity of cell cycle related proteins. Constitutive activation of many signal transduction pathways also stimulates cell growth. Early steps in tumor development are associated with a fibrogenic response and the development of a hypoxic environment which favors the survival and proliferation of cancer stem cells. Part of the survival strategy of cancer stem cells may manifested by alterations in cell metabolism. Once tumors appear, growth and metastasis may be supported by overproduction of appropriate hormones (in hormonally dependent cancers), by promoting angiogenesis, by undergoing epithelial to mesenchymal transition, by triggering autophagy, and by taking cues from surrounding stromal cells. A number of natural compounds (e.g., curcumin, resveratrol, indole-3-carbinol, brassinin, sulforaphane, epigallocatechin-3-gallate, genistein, ellagitannins, lycopene and quercetin) have been found to inhibit one or more pathways that contribute to proliferation (e.g., hypoxia inducible factor 1, nuclear factor kappa B, phosphoinositide 3 kinase/Akt, insulin-like growth factor receptor 1, Wnt, cell cycle associated proteins, as well as androgen and estrogen receptor signaling). These data, in combination with bioinformatics analyses, will be very important for identifying signaling pathways and molecular targets that may provide early diagnostic markers and/or critical targets for the development of new drugs or drug combinations that block tumor formation and progression

Insights into Eyestalk Ablation Mechanism to Induce Ovarian Maturation in the Black Tiger Shrimp

Eyestalk ablation is commonly practiced in crustacean to induce ovarian maturation in captivity. The molecular mechanism of the ablation has not been well understood, preventing a search for alternative measures to induce ovarian maturation in aquaculture. This is the first study to employ cDNA microarray to examine effects of eyestalk ablation at the transcriptomic level and pathway mapping analysis to identify potentially affected biological pathways in the black tiger shrimp (Penaeus monodon). Microarray analysis comparing between gene expression levels of ovaries from eyestalk-intact and eyestalk-ablated brooders revealed 682 differentially expressed transcripts. Based on Hierarchical clustering of gene expression patterns, Gene Ontology annotation, and relevant functions of these differentially expressed genes, several gene groups were further examined by pathway mapping analysis. Reverse-transcriptase quantitative PCR analysis for some representative transcripts confirmed microarray data. Known reproductive genes involved in vitellogenesis were dramatically increased during the ablation. Besides these transcripts expected to be induced by the ablation, transcripts whose functions involved in electron transfer mechanism, immune responses and calcium signal transduction were significantly altered following the ablation. Pathway mapping analysis revealed that the activation of gonadotropin-releasing hormone signaling, calcium signaling, and progesterone-mediated oocyte maturation pathways were putatively crucial to ovarian maturation induced by the ablation. These findings shed light on several possible molecular mechanisms of the eyestalk ablation effect and allow more focused investigation for an ultimate goal of finding alternative methods to replace the undesirable practice of the eyestalk ablation in the future

Targeted Manipulation of Serotonergic Neurotransmission Affects the Escalation of Aggression in Adult Male Drosophila melanogaster

Dopamine (DA) and serotonin (5HT) are reported to serve important roles in aggression in a wide variety of animals. Previous investigations of 5HT function in adult Drosophila behavior have relied on pharmacological manipulations, or on combinations of genetic tools that simultaneously target both DA and 5HT neurons. Here, we generated a transgenic line that allows selective, direct manipulation of serotonergic neurons and asked whether DA and 5HT have separable effects on aggression. Quantitative morphological examination demonstrated that our newly generated tryptophan hydroxylase (TRH)-Gal4 driver line was highly selective for 5HT-containing neurons. This line was used in conjunction with already available Gal4 driver lines that target DA or both DA and 5HT neurons to acutely alter the function of aminergic systems. First, we showed that acute impairment of DA and 5HT neurotransmission using expression of a temperature sensitive form of dynamin completely abolished mid- and high-level aggression. These flies did not escalate fights beyond brief low-intensity interactions and therefore did not yield dominance relationships. We showed next that manipulation of either 5HT or DA neurotransmission failed to duplicate this phenotype. Selective disruption of 5HT neurotransmission yielded flies that fought, but with reduced ability to escalate fights, leading to fewer dominance relationships. Acute activation of 5HT neurons using temperature sensitive dTrpA1 channel expression, in contrast, resulted in flies that escalated fights faster and that fought at higher intensities. Finally, acute disruption of DA neurotransmission produced hyperactive flies that moved faster than controls, and rarely engaged in any social interactions. By separately manipulating 5HT- and DA- neuron systems, we collected evidence demonstrating a direct role for 5HT in the escalation of aggression in Drosophila

Brain architecture in the terrestrial hermit crab Coenobita clypeatus (Anomura, Coenobitidae), a crustacean with a good aerial sense of smell

<p>Abstract</p> <p>Background</p> <p>During the evolutionary radiation of Crustacea, several lineages in this taxon convergently succeeded in meeting the physiological challenges connected to establishing a fully terrestrial life style. These physiological adaptations include the need for sensory organs of terrestrial species to function in air rather than in water. Previous behavioral and neuroethological studies have provided solid evidence that the land hermit crabs (Coenobitidae, Anomura) are a group of crustaceans that have evolved a good sense of aerial olfaction during the conquest of land. We wanted to study the central olfactory processing areas in the brains of these organisms and to that end analyzed the brain of <it>Coenobita clypeatus </it>(Herbst, 1791; Anomura, Coenobitidae), a fully terrestrial tropical hermit crab, by immunohistochemistry against synaptic proteins, serotonin, FMRFamide-related peptides, and glutamine synthetase.</p> <p>Results</p> <p>The primary olfactory centers in this species dominate the brain and are composed of many elongate olfactory glomeruli. The secondary olfactory centers that receive an input from olfactory projection neurons are almost equally large as the olfactory lobes and are organized into parallel neuropil lamellae. The architecture of the optic neuropils and those areas associated with antenna two suggest that <it>C. clypeatus </it>has visual and mechanosensory skills that are comparable to those of marine Crustacea.</p> <p>Conclusion</p> <p>In parallel to previous behavioral findings of a good sense of aerial olfaction in C. clypeatus, our results indicate that in fact their central olfactory pathway is most prominent, indicating that olfaction is a major sensory modality that these brains process. Interestingly, the secondary olfactory neuropils of insects, the mushroom bodies, also display a layered structure (vertical and medial lobes), superficially similar to the lamellae in the secondary olfactory centers of <it>C. clypeatus</it>. More detailed analyses with additional markers will be necessary to explore the question if these similarities have evolved convergently with the establishment of superb aerial olfactory abilities or if this design goes back to a shared principle in the common ancestor of Crustacea and Hexapoda.</p