Role of the protein moiety of ribonuclease P, a ribonucleoprotein enzyme

The Bacillus subtilis ribonuclease P consists of a protein and an RNA. At high ionic strength the reaction is protein-independent; the RNA alone is capable of cleaving precursor transfer RNA, but the turnover is slow. Kinetic analyses show that high salt concentrations facilitate substrate binding in the absence of the protein, probably by decreasing the repulsion between the polyanionic enzyme and substrate RNAs, and also slow product release and enzyme turnover. It is proposed that the ribonuclease P protein, which is small and basic, provides a local pool of counter-ions that facilitates substrate binding without interfering with rapid product release.     

Cutaneous neoplasia in 340 cats.

A total of 340 cases of cutaneous neoplasia were diagnosed in 340 of 3,564 cats that were examined by biopsy or necropsy during a 41-month period from January 1, 1986 through May 31, 1989. Eighteen types of tumor occurred, but four types comprised 77% of the cases. These were basal cell tumor, 89 cases (26%, mean age 10.3); mast cell tumor, 72 cases (21%, mean age 8.6); squamous cell carcinoma, 52 cases (15%, mean age 11.6); and fibrosarcoma, 50 cases (15%, mean age 10.2). For each of these four types of tumors, peak number of cases occurred in cats older than 10 years. Mast cell tumor was the only tumor diagnosed in cats younger than 1 year. The head was the most common site for basal cell tumors, mast cell tumors, and squamous cell carcinomas. The legs were the most common location of fibrosarcomas. Siamese cats had approximately three times as many mast cell tumors as statistically expected, but only one-fourth as many squamous cell carcinomas. Breed predilection for other skin tumors was not apparent. Sex predilection was not detected for any skin tumor.     

Biosatellite 3. Preliminary findings

Physiological deterioration in the male macaque monkey flown in Biosatellite III necessitated its recall after 8.5 days of a planned 30-day flight. For the first 7 days the only telemetered signs of a progressive general decline were falling brain temperature and lowered central venous pressure, which occurred in the last 3 days of flight. Fluid loss in flight was high, caused initially by sweating and later by diuresis, and appeared to arise in redistribution of blood in visceral pools as a consequence of weightlessness. Death occurred suddenly 12 hours after the flight and was caused by ventricular fibrillation.     

Synchronous climate changes in antarctica and the north atlantic

Central Greenland ice cores provide evidence of abrupt changes in climate over the past 100,000 years. Many of these changes have also been identified in sedimentary and geochemical signatures in deep-sea sediment cores from the North Atlantic, confirming the link between millennial-scale climate variability and ocean thermohaline circulation. It is shown here that two of the most prominent North Atlantic events-the rapid warming that marks the end of the last glacial period and the Bolling/Allerod-Younger Dryas oscillation-are also recorded in an ice core from Taylor Dome, in the western Ross Sea sector of Antarctica. This result contrasts with evidence from ice cores in other regions of Antarctica, which show an asynchronous response between the Northern and Southern Hemispheres.     

In vitro synthesis of an infectious mutant RNA with a normal RNA replicase

When purified Qbeta-RNA replicase is presented alternately with two genetically different Qbeta-RNA molecules, the RNA synthesized is identical to the initiating template. The results establish that the RNA is the instructive agent in the replicative process and hence that it satisfies the operational definition of a self-duplicating entity. The data also eliminate alternative explanations which do not involve self-propagation of the input RNA. An opportunity is now provided for studying the genetics and evolution of a self-duplicating nucleic acid molecule under conditions permitting detailed control of environmental parameters and chemical components.     

Ribonuclease P catalysis differs from ribosomal RNA self-splicing

Two RNA-catalyzed reactions have been described, the Tetrahymena self-splicing ribosomal RNA and ribonuclease P. The Tetrahymena self-splicing reaction proceeds through a transesterification cascade that is dependent upon nucleophilic attacks by ribose 3'-OH groups. Periodate oxidation of the catalytic (or substrate) RNA, which destroys the nucleophilicity of RNA 3' termini, did not inhibit ribonuclease P activity. Thus, catalysis by ribonuclease P differs from the self-splicing reaction.     

The decline of short-beaked common dolphin (Delphinus delphis) in the waters off the island of Ischia (Gulf of Naples,Italy)

1. This study presents data on a local population of short-beaked common dolphin monitored in the waters off Ischia Island (Gulf of Naples, Italy) over a 16-year period (2000-2015). We examine dolphin occurrence and distribution and perform photoidentification analysis.
2. The data presented support the hypothesis that the waters around Ischia Island represent a feeding area, as well as a calving and an important nursery area for this local population, providing favourable conditions in which to give birth and raise calves.
3. The levelling-off of the photoidentification curves together with the continuous decline of the encounter rate lead us to believe that the area has been a hotspot for a local population (mainly resident) for years and that now this population is dying (has died) or is moving (has moved) to other locations.
4. Several expanding human activities at sea have the potential to impact on the common dolphin in the study area, the most significant possibly being habitat disturbance and degradation (including traffic and noise pollution) and overexploitation of food resources by the fishery.
5. The data presented in this study offer a strong argument for explicit and urgent population-specific conservation and management strategies to be developed and applied locally for common dolphins, considering that they rely on the region for important biological processes.

     

Retrospective study of 338 canine oral melanomas with clinical, histologic, and immunohistochemical review of 129 cases

Diagnostic records from 338 canine oral melanomas in 338 dogs received at the Veterinary Medical Diagnostic Laboratory (1992-1999) were reviewed. Of these tumors, 122 plus an additional 7 metastatic melanomas of unknown origin were selected for clinical follow-up, histologic review, and immunohistochemistry. Chow Chow, Golden Retriever, and Pekingese/Poodle mix breeds were overrepresented, whereas Boxer and German Shepherd breeds were underrepresented. There was no gender predisposition and the average age at presentation was 11.4 years. Forty-nine dogs were euthanized due to recurrence or metastasis. The average postsurgical survival time was 173 days. The gingiva and the labial mucosa were the most common sites. Most tumors were composed of either polygonal cells (27 cases, 20.9%), spindle cells (44 cases, 34.1%), or a mixture of the two (polygonal and spindle) (54 cases, 41.9%). Clear cell (3 cases, 2.3%) and adenoid/papillary (1 case, 0.8%) patterns were uncommon. The metastases of 6/6 oral melanomas had morphologic and immunohistochemical features similar to those of the primary tumors. Immunohistochemically, Melan A was detected in 113/122 oral (92.6%) and 5/7 (71.9%) metastatic melanomas. Only 4/163 nonmelanocytic tumors were focally and weakly positive for Melan A. Antibodies against vimentin, S100 protein, and neuron-specific enolase stained 129 (100%), 98 (76%), and 115 (89.1%) of 129 melanomas, respectively. Antibodies against other melanocytic-associated antigens (tyrosinase, glycoprotein 100) did not yield adequate staining. We conclude that Melan A is a specific and sensitive marker for canine melanomas.