Cooperativity of Rb,Brca1, and p53 in Malignant Breast Cancer Evolution

Breast cancers that are “triple-negative” for the clinical markers ESR1, PGR, and HER2 typically belong to the Basal-like molecular subtype. Defective Rb, p53, and Brca1 pathways are each associated with triple-negative and Basal-like subtypes. Our mouse genetic studies demonstrate that the combined inactivation of Rb and p53 pathways is sufficient to suppress the physiological cell death of mammary involution. Furthermore, concomitant inactivation of all three pathways in mammary epithelium has an additive effect on tumor latency and predisposes highly penetrant, metastatic adenocarcinomas. The tumors are poorly differentiated and have histologic features that are common among human Brca1-mutated tumors, including heterogeneous morphology, metaplasia, and necrosis. Gene expression analyses demonstrate that the tumors share attributes of both Basal-like and Claudin-low signatures, two molecular subtypes encompassed by the broader, triple-negative class defined by clinical markers.     

The Maloti minnow Pseudobarbus quathlambae (Barnard, 1938) is not extinct in South Africa

Despite concerted surveys, the Maloti minnow Pseudobarbus quathlambae (Barnard 1938) had not been recorded in South African waters for almost eighty years since the original collections were made at the type locality in the upper uMkhomazana River in 1938. The species was therefore declared extinct in South Africa, whereas extant populations were considered confined to various rivers in the Lesotho highlands. In April 2017, however, this species was rediscovered in the Mzimkhulu River system in KwaZulu-Natal. The rediscovery of a species that was considered locally extinct supports the need for extensive surveys to determine its distribution range, estimate population sizes, assess conservation status and implement effective strategies to ensure its continued existence in KwaZulu-Natal.     

Chromosome Rearrangements in CAENORHABDITIS ELEGANS

A method for selecting unlinked duplications of a part of the X chromosome of C. elegans is described. Five such duplications have been identified. One of them, Dp (X;V)1, is translocated to linkage group V, where it suppresses crossing over along the left half of linkage group V. Dp(X;V)1 homozygotes grow slowly and are sterile. The other four duplications are associated with chromosome fragments, as observed cytologically by fluorescence microscopy, and tend to be lost. Their frequency of loss is higher in strains homozygous for a mutation that promotes nondisjunction of X chromosomes. The recombination frequencies between two of these duplications and the X have been measured: the frequencies are at least 50 times less than for X-X recombination in the same region. The duplications may prove useful as balancers of recessive lethal mutations.     

Contributing factor toMycoplasma pneumoniae produced stimulation of rhinovirus-RNA synthesis

It has been demonstrated thatRhinovirus ribonucleic acid (RNA) synthesis was greater inMycoplasma pneumoniae inoculated KB (Human Carcinoma of Nasopharynx) cells than in PPLO-free tissue systems (Milligan III & Fletcher, 1969). In this study,Mycoplasma pneumoniae was grown on glass to eliminate the PPLO medium. However, if PPLO medium was added to theMycoplasma pneumoniae inoculum, stimulation of viral-RNA synthesis was greater than in the presence of PPLO alone. Rhinovirus-RNA synthesis, measured by uridine-³H uptake, in the presence ofMycoplasma pneumoniae andMycoplasma pneumoniae plus medium was enhanced 1.2-fold and 1.4-fold respectively, above virus synthesis in untreated KB cell systems. PPLO medium did not appear to significantly stimulate viral RNA synthesis. However, a 5-fold increase in the concentration of the medium or its components resulted in greater viral RNA replication. The medium components, yeast extract and PPLO broth (Difco), stimulated viral RNA synthesis 4-fold and 2-fold, respectively. Our findings also demonstrated that other components, agar, phenol red, and dextrose, inhibited viral replication, whereas horse serum appeared to have no effect. This work was supported by the Life Sciences Division of the U.S. Army Research Office under contract/grant No. DAHC-20-67C-0122/DAHC 19-69-G-0011.     

Life histories and production of three Rocky Mountain aquatic insects along an elevation-driven temperature gradient

Hydrobiologia - Although temperature is known to influence individual traits such as growth, body size, and fecundity, few studies have examined how these relationships influence population-level...