Nautilus
Petrolatum
Coral Reefs
Mollusca
Novel iridovirus in a nautilus (Nautilus spp.). (1/10)
Intracytoplasmic inclusion bodies suggestive of iridovirus infection were observed in formalin-fixed, paraffin-embedded tissues from a nautilus (Nautilus spp.) that died without premonitory signs. Transmission electron microscopy revealed enveloped, hexagonal, viral particles that measured approximately 176 nm in diameter. Virions contained a dense central core and morphology typical of iridoviruses. Extracted DNA was amplified using primers homologous to conserved iridovirus sequences. The amplicons were cloned, sequenced, and determined to be approximately 60% similar to reported amphibian iridovirus sequences. A polymerase chain reaction-generated digoxigenin probe was used to detect viral nucleic acid in tissue sections by DNA in situ hybridization and high-affinity cytochemistry. The detected nucleic acid corresponded to the inclusion bodies observed microscopically. This represents a novel iridovirus of mollusks. (+info)The complete sequence of the mitochondrial genome of Nautilus macromphalus (Mollusca: Cephalopoda). (2/10)
BACKGROUND: Mitochondria contain small genomes that are physically separate from those of nuclei. Their comparison serves as a model system for understanding the processes of genome evolution. Although complete mitochondrial genome sequences have been reported for more than 600 animals, the taxonomic sampling is highly biased toward vertebrates and arthropods, leaving much of the diversity yet uncharacterized. RESULTS: The mitochondrial genome of the bellybutton nautilus, Nautilus macromphalus, a cephalopod mollusk, is 16,258 nts in length and 59.5% A+T, both values that are typical of animal mitochondrial genomes. It contains the 37 genes that are almost universally found in animal mtDNAs, with 15 on one DNA strand and 22 on the other. The arrangement of these genes can be derived from that of the distantly related Katharina tunicata (Mollusca: Polyplacophora) by a switch in position of two large blocks of genes and transpositions of four tRNA genes. There is strong skew in the distribution of nucleotides between the two strands, and analysis of this yields insight into modes of transcription and replication. There is an unusual number of non-coding regions and their function, if any, is not known; however, several of these demark abrupt shifts in nucleotide skew, and there are several identical sequence elements at these junctions, suggesting that they may play roles in transcription and/or replication. One of the non-coding regions contains multiple repeats of a tRNA-like sequence. Some of the tRNA genes appear to overlap on the same strand, but this could be resolved if the polycistron were cleaved at the beginning of the downstream gene, followed by polyadenylation of the product of the upstream gene to form a fully paired structure. CONCLUSION: Nautilus macromphalus mtDNA contains an expected gene content that has experienced few rearrangements since the evolutionary split between cephalopods and polyplacophorans. It contains an unusual number of non-coding regions, especially considering that these otherwise often are generated by the same processes that produce gene rearrangements. The skew in nucleotide composition between the two strands is strong and associated with the direction of transcription in various parts of the genomes, but a comparison with K. tunicata implies that mutational bias during replication also plays a role. This appears to be yet another case where polyadenylation of mitochondrial tRNAs restores what would otherwise be an incomplete structure. (+info)Enigmatic dual symbiosis in the excretory organ of Nautilus macromphalus (Cephalopoda: Nautiloidea). (3/10)
Symbiosis is an important driving force in metazoan evolution and the study of ancient lineages can provide an insight into the influence of symbiotic associations on morphological and physiological adaptations. In the 'living fossil' Nautilus, bacterial associations are found in the highly specialized pericardial appendage. This organ is responsible for most of the excretory processes (ultrafiltration, reabsorption and secretion) and secretes an acidic ammonia-rich excretory fluid. In this study, we show that Nautilus macromphalus pericardial appendages harbour a high density of a beta-proteobacterium and a coccoid spirochaete using transmission electron microscopy, comparative 16S rRNA sequence analysis and fluorescence in situ hybridization (FISH). These two bacterial phylotypes are phylogenetically distant from any known bacteria, with ammonia-oxidizing bacteria as the closest relatives of the beta-proteobacterium (above or equal to 87.5% sequence similarity) and marine Spirochaeta species as the closest relatives of the spirochaete (above or equal to 89.8% sequence similarity), and appear to be specific to Nautilus. FISH analyses showed that the symbionts occur in the baso-medial region of the pericardial villi where ultrafiltration and reabsorption processes take place, suggesting a symbiotic contribution to the excretory metabolism. (+info)A biphasic memory curve in the chambered nautilus, Nautilus pompilius L. (Cephalopoda: Nautiloidea). (4/10)
(+info)Nautilus pompilius life history and demographics at the Osprey Reef Seamount, Coral Sea, Australia. (5/10)
(+info)Nautilus at risk--estimating population size and demography of Nautilus pompilius. (6/10)
(+info)Vertical distribution and migration patterns of Nautilus pompilius. (7/10)
(+info)Old and sticky-adhesive mechanisms in the living fossil Nautilus pompilius (Mollusca, Cephalopoda). (8/10)
(+info)I'm sorry for any confusion, but "Nautilus" is not a medical term. It is a genus of cephalopod mollusk known as nautiloids, which are marine animals. The Nautilus species is the only living member of the family Nautilidae and one of the few cephalopods to exhibit a spiral shell.
If you have any medical concerns or questions, I'd be happy to help if you could provide a medical term for me to define.
Petrolatum is a semi-solid mixture of hydrocarbons obtained from petroleum. In the medical field, it's often used as an ointment base or protective dressing because of its impermeability to water and bacteria. It's also known as petroleum jelly or soft paraffin.
Coral reefs are complex, underwater ecosystems formed by the accumulation of calcium carbonate structures secreted by colonies of corals. They provide habitat and protection for a wide variety of marine organisms, including fish, mollusks, crustaceans, and other invertebrates.
Coral reefs are found in shallow, tropical waters around the world, and they are often referred to as the "rainforests of the sea" due to their incredible biodiversity. They are formed over thousands of years as corals grow and reproduce, gradually building up layers of calcium carbonate structures known as skeletons.
There are several different types of coral reefs, including fringing reefs, barrier reefs, and atolls. Fringing reefs are located close to the shore and are often found in areas with steep drop-offs. Barrier reefs are larger than fringing reefs and are separated from the shore by a lagoon or a body of water. Atolls are circular or ring-shaped reefs that surround a central lagoon.
Coral reefs provide many important ecosystem services, including coastal protection, nutrient cycling, and support for fisheries. However, they are facing numerous threats from human activities such as overfishing, pollution, and climate change, which can lead to coral bleaching and death. Conservation efforts are underway to protect and restore these valuable ecosystems.
Mollusca is not a medical term per se, but a major group of invertebrate animals that includes snails, clams, octopuses, and squids. However, medically, some mollusks can be relevant as they can act as vectors for various diseases, such as schistosomiasis (transmitted by freshwater snails) and fascioliasis (transmitted by aquatic snails). Therefore, a medical definition might describe Mollusca as a phylum of mostly marine invertebrates that can sometimes play a role in the transmission of certain infectious diseases.