Antibiotic Treatment of Mucodegeneration and Positive Buoyancy in a Chambered Nautilus Nautilus pompilius.

The correct diagnosis and treatment of disease in chambered nautiluses Nautilus pompilius are difficult. The basic morphology and natural behaviors of the species tend to mask the initial onset of a disease or infection, and by the time it is observable, mortality usually occurs. A single specimen of chambered nautilus at the Museum of Nature South Tyrol, Italy, exhibited symptoms of an infection, including mucus production, abnormal buoyancy, irregular hood appearance, and inconsistent tentacle movement. Soon after, tetracycline hydrochloride was administered in bath form at 25 mg/L in seawater daily for 30 min over six consecutive days. The specimen regained normal buoyancy after the fifth day. After the 6-d treatment, the specimen regained all normal behaviors and appearance within 2 weeks. More than 1 year after treatment, the specimen was exhibiting normal behaviors with no adverse reactions. When administered soon after symptoms of an infection were observed, tetracycline was effective at halting the progression of symptoms and led to the full recovery of the chambered nautilus.

First report of a successful treatment of a mucodegenerative disease in the chambered nautilus (Nautilus pompilius).

A single Nautilus pompilius manifested a bacterial infection and nematode infestation soon after it was received from the wild, resulting in a significant buildup of mucus above the left eye and tentacles. This condition is known to lead to rapid mucodegeneration of the tentacles and epithelium, resulting in death. The specimen was quarantined 24 days after arrival. Initial topical treatments of 10% povidone solution were effective at slowing the progression of the mucus but did not eliminate it. After 26 days in quarantine, a new treatment regimen was developed that coupled a whole-animal dip in 25 mg/L oxytetracycline solution with the 10% povidone treatment on alternate days, for 5 days. After this treatment, mucus production ceased and nematodes were not present in tissue samples. The specimen was moved back to the original holding system after a quarantine period of 53 days.

Enigmatic dual symbiosis in the excretory organ of Nautilus macromphalus (Cephalopoda: Nautiloidea).

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.