ABSTRACT
Scaling of nuclear size with cell size has been observed in many species and cell types. In this work we formulate a modeling framework based on the limiting component hypothesis. We derive a family of spatio-temporal mathematical models for nuclear size determination based on different transport and growth mechanisms. We analyse model properties and use in vitro experimental data to identify the most probable mechanism. This suggests that nuclear volume scales with cell volume and that a nucleus controls its import rate as it grows. We further test the model by comparing to data of early frog development, where rapid cell divisions set the relevant time scales.
Subject(s)
Cell Nucleus , Models, Theoretical , Cell Size , Cytoplasm , CytosolABSTRACT
The infectious laryngotracheitis virus (ILTV) gene encoding a homologue to the glycoprotein C gene of herpes simplex virus has been sequenced and identified based on its genomic location, comparative analysis to other gC proteins, and the identification of a glycosylated protein product. Located near the small subunit ribonucleotide reductase gene, the ILTV gC gene is 1242 bp in length and is predicted to encode a membrane glycoprotein containing a characteristic N-terminal hydrophobic signal sequence, five potential N-linked glycosylation sites, and C-terminal transmembrane and cytoplasmic domains. Antibodies raised in rabbits against a Cro-ILTV-beta-galactosidase fusion protein expressed in Escherichia coli recognize a 60-kDa ILTV-specific glycoprotein from infected cell extracts. Transcriptional analysis, using a portion of the open reading frame as a probe, identified a 1.55-kb transcript expressed with late gene kinetics. Comparison to other herpesvirus gC proteins revealed limited amino acid sequence homology and the absence of a charged extracellular region, which would normally interact with cell surface proteoglycans.
Subject(s)
Alphaherpesvirinae/genetics , Bird Diseases/microbiology , Genes, Viral , Laryngitis/veterinary , Tracheitis/veterinary , Viral Envelope Proteins/genetics , Alphaherpesvirinae/chemistry , Amino Acid Sequence , Animals , Base Sequence , Laryngitis/microbiology , Molecular Sequence Data , Tracheitis/microbiology , Transcription, Genetic , Viral Envelope Proteins/analysis , Viral Envelope Proteins/chemistryABSTRACT
Restriction endonuclease (RE) digestion patterns of six Delmarva field isolates of infectious laryngotracheitis virus (ILTV) were compared with three standard reference strains. With one exception, all of the field isolates generated RE digestion patterns identical to an embryo-propagated vaccine strain of ILTV when the six-base-recognizing REs EcoRI, HindIII, PstI, and BamHI were used. In order to increase the sensitivity of the RE analysis technique, a more sensitive DNA fingerprinting approach using four-base-recognizing enzymes was developed. One field isolate could be differentiated from the embryo-propagated vaccine strain using all three enzymes, Sau3AI, MspI, and HinfI. A second isolate could be differentiated only by comparing HinfI digestion patterns. This work provides additional evidence that differentiable strains of ILTV exist in the United States. Furthermore, currently used RE analysis methods may not be sensitive enough to discriminate between field isolates and vaccine strains of ILTV, thus challenging the theory that vaccine strains of ILTV are responsible for field outbreaks of infectious laryngotracheitis.
