Prevention of apoptosis by a baculovirus gene during infection of insect cells

Programmed cell death is an active process of self destruction that is important in both the development and maintenance of multicellular animals. The molecular mechanisms controlling activation or suppression of programmed cell death are largely unknown. Apoptosis, a morphologically and biochemically defined type of programmed cell death commonly seen in vertebrates, was found to be initiated during baculovirus replication in insect cells. A specific viral gene product, p35, was identified as being responsible for blocking the apoptotic response. Identification of the function of this gene will allow further definition of the molecular pathways involved in the regulation of programmed cell death and may identify the role of apoptosis in invertebrate viral defense systems.     

Artificial Feeding of Neonatal Rats

Newborn rats, fed either cow's milk or rat's milk by tube, developed a "bloat" and the time required for emptying the stomach increased. When these animals were allowed to suckle on nonlactating foster mothers, no evidence of this syndrome was observed. Based on these observations, a technique was developed for the artificial feeding of newborn rats. When the diet was rat's milk, growth equivalent to that of animals fed solely by lactating females was obtained. A diet of cow's milk did not support adequate growth.     

Endotoxin: stimulation of bone resorption in tissue culture

Bacterial endotoxins can stimulate the release of previously incorporated calcium-45 and tritiated proline from fetal rat bone in tissue culture. Endotoxin from Bacteroides melaninogenicus, an organism regularly found in the gingival crevice of man, produces a response similar to parathyroid hormone and is effective at doses as low as 0.1 microgram per milliliter. This response is inhibited by serum and dependent upon the presence of albumin. Endotoxins may play a role in the bone loss characteristic of human periodontal disease.     

Comment on "Retrieval practice produces more learning than elaborative studying with concept mapping"

Karpicke and Blunt (Reports, 11 February 2011, p. 772) reported that retrieval practice produces greater gains in learning than elaborative studying with concept mapping and concluded that this strategy is a powerful way to promote meaningful learning of complex concepts commonly found in science education. We question their findings on methodological and epistemological grounds.     

The Phanerozoic record of global sea-level change

We review Phanerozoic sea-level changes [543 million years ago (Ma) to the present] on various time scales and present a new sea-level record for the past 100 million years (My). Long-term sea level peaked at 100 +/- 50 meters during the Cretaceous, implying that ocean-crust production rates were much lower than previously inferred. Sea level mirrors oxygen isotope variations, reflecting ice-volume change on the 10(4)- to 10(6)-year scale, but a link between oxygen isotope and sea level on the 10(7)-year scale must be due to temperature changes that we attribute to tectonically controlled carbon dioxide variations. Sea-level change has influenced phytoplankton evolution, ocean chemistry, and the loci of carbonate, organic carbon, and siliciclastic sediment burial. Over the past 100 My, sea-level changes reflect global climate evolution from a time of ephemeral Antarctic ice sheets (100 to 33 Ma), through a time of large ice sheets primarily in Antarctica (33 to 2.5 Ma), to a world with large Antarctic and large, variable Northern Hemisphere ice sheets (2.5 Ma to the present).