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J E Larsen

Publications and source records attributed to J E Larsen.

16 recordsLinked to original sources
PubMed2000

Apical and non-polarized secretion of serpins from MDCK cells.

Corticosteroid binding globulin, a member of the serpin family, was previously shown to be secreted mainly apically from MDCK cells in an N-glycan independent manner [Larsen et al. (1999) FEBS Lett. 451, 19-22]. Apart from N-glycosylation, serpins are not known to carry any other posttranslational modifications, suggesting the presence of a proteinaceous apical sorting signal. In the present study we have expressed four other members of the serpin family: alpha1-antitrypsin, C1 inhibitor, plasminogen activator inhibitor-1 and antithrombin in MDCK cells. Tight monolayers of transfected cells were grown on filters and the amounts of recombinantly expressed serpins in the apical and the basolateral media were determined. alpha1-Antitrypsin and C1 inhibitor were found mainly in the apical medium whereas plasminogen activator inhibitor-1 and antithrombin were found in roughly equal amounts in the apical and basolateral media. Control experiments showed that all four serpins are transported along the exocytotic pathway in an uncomplicated way that does not involve transcytosis or differences in stability on the two sides of the cells. We conclude that some members of the serpin family including corticosteroid binding globulin, alpha1-antitrypsin and C1 inhibitor are secreted mainly apically from MDCK cells whereas plasminogen activator inhibitor-1 and antithrombin are secreted in a non-polarized manner.

Amino Acid Sequence↗
PubMed2000

Pax gene diversity in the basal cnidarian Acropora millepora (Cnidaria, Anthozoa): implications for the evolution of the Pax gene family.

Pax genes encode a family of transcription factors, many of which play key roles in animal embryonic development but whose evolutionary relationships and ancestral functions are unclear. To address these issues, we are characterizing the Pax gene complement of the coral Acropora millepora, an anthozoan cnidarian. As the simplest animals at the tissue level of organization, cnidarians occupy a key position in animal evolution, and the Anthozoa are the basal class within this diverse phylum. We have identified four Pax genes in Acropora: two (Pax-Aam and Pax-Bam) are orthologs of genes identified in other cnidarians; the others (Pax-Cam and Pax-Dam) are unique to Acropora. Pax-Aam may be orthologous with Drosophila Pox neuro, and Pax-Bam clearly belongs to the Pax-2/5/8 class. The Pax-Bam Paired domain binds specifically and preferentially to Pax-2/5/8 binding sites. The recently identified Acropora gene Pax-Dam belongs to the Pax-3/7 class. Clearly, substantial diversification of the Pax family occurred before the Cnidaria/higher Metazoa split. The fourth Acropora Pax gene, Pax-Cam, may correspond to the ancestral vertebrate Pax gene and most closely resembles Pax-6. The expression pattern of Pax-Cam, in putative neurons, is consistent with an ancestral role of the Pax family in neural differentiation and patterning. We have determined the genomic structure of each Acropora Pax gene and show that some splice sites are shared both between the coral genes and between these and Pax genes in triploblastic metazoans. Together, these data support the monophyly of the Pax family and indicate ancient origins of several introns.

Amino Acid Sequence↗
PubMed1999

N-glycans are not the signal for apical sorting of corticosteroid binding globulin in MDCK cells.

It has been suggested that N-glycans act as a general sorting signal for secretory proteins in MDCK cells [Scheiffele et al. (1995) Nature 378, 96-98]. Human corticosteroid binding globulin contains six consensus sites for N-glycosylation and is known to be secreted to the apical side of MDCK cells. Our results show that wild-type corticosteroid binding globulin is N-glycosylated when it is recombinantly expressed in MDCK cells. Six mutants, each lacking one of the N-glycosylation sites, and a mutant lacking all six N-glycosylation sites were also secreted to the apical side of MDCK cells in a polarized manner. Thus, the N-glycans on corticosteroid binding globulin do not act as an apical sorting signal in MDCK cells.

Animals↗
PubMed1994

Aging and episodic memory: are elderly adults less likely to make connections between target and contextual information?

The hypothesis that elderly individuals are less likely than young adults to connect target and contextual information was tested. Young and elderly adults were presented with a number of slides, each of which contained a word superimposed in the center of a background picture of a landscape or cityscape. Half of the subjects were told to remember the words and half were told to remember the word-and-background pairs. All subjects were then tested for their recognition memory of the word-and-background pairs. The results indicate that elderly adults have greater difficulty than young adults remembering the connections between words and background pictures but that this occurs whether the pictures are target information or contextual information. Therefore, the results of this study provide no support for the notion that elderly adults have a specific contextual encoding deficit.

Adult↗
PubMed1987

Analysis of the terminator region after the deoCABD operon of Escherichia coli K-12 using a new class of single copy number operon-fusion vectors.

We describe the construction of low copy number operon-fusion vectors, and use one of these vectors for the cloning and transcriptional analysis of the terminator region after the deo operon of Escherichia coli K-12. The new vectors are miniderivatives of plasmid R1 containing the parB stability locus of this plasmid and the lac genes as a selectable marker. Since the copy number of the vectors is only one per genome-equivalent at temperatures below 37 degrees C this system is ideally suited for isolation and characterization of transcriptional and translational signals from E. coli. Our results show that a very strong terminator (deot), which resembles Rho-independent terminators, is located 60 bp downstream from the fourth structural gene of the deo operon. This confirms that deoD is the last gene in the operon. In addition, we have identified a new promoter just after the deot terminator and a short DNA sequence that is able to reduce lacZ expression by 85% when inserted between the deoP2 promoter and the lac genes.

Base Sequence↗
PubMed1987

Processing yields and meat flavor of broilers fed a mixture of narasin and nicarbazin as an anticoccidial agent.

Processed yields (percent hot carcass) and cooked meat flavor of broilers fed 100 ppm of an anticoccidial agent (a mixture of 50 ppm narasin and 50 ppm nicarbazin) were compared with yields of birds fed a ration without the anticoccidial agent. Broilers were processed at 7 wk of age (49 days) after a 4-day withdrawal from the anticoccidial agent for the treated birds. The flavor of meat was evaluated by a 12-member sensory panel. Meat was either deep fat-fried or oven roasted. Sensory evaluations were made on freshly cooked samples and on cooked meat refrigerated for 24 h and reheated. The anticoccidial agent did not produce a difference (P greater than .05) in the hot carcass yields of the broilers as compared with control birds fed the nonmedicated diet. Analyses of triangle test data for flavor evaluations by two statistical methods indicated that there were no detectable differences (P greater than .05) in flavor between broilers fed the anticoccidial agent in the diet and those fed the control diet.

Animals↗
PubMed1986

Nucleotide sequence of the CytR regulatory gene of E. coli K-12.

We have determined the nucleotide sequence of the cytR gene, which codes for the Cyt repressor (CytR). The coding region consists of 1023 or 1029 bp. The subunits of CytR are thus predicted to consist of 341 or 343 residues. It is shown that the N-terminal segment of the polypeptide is structurally similar to the DNA-binding region of known DNA-binding proteins. In addition, there exists an exceptionally high amino acid sequence homology between CytR and the Gal repressor, indicating a common origin of evolution.

Amino Acid Sequence↗
PubMed1986

Comparison of two lighting regimens and drinker cleaning programmes on the performance and incidence of leg abnormalities in turkey males.

Turkey males subjected to a low intensity step-down (LISD) lighting programme showed significantly heavier body weights after 20 weeks of age and significantly better feed conversions after 14 weeks of age compared with males reared in a high intensity step-up lighting (HISU) programme. Although both nonchilled and chilled carcase weights were higher, the dressing percentages were lower for males of the LISD lighting regimen. Males of the HISU lighting programme had significantly fewer leg abnormalities, shorter tarso-metatarsi, lighter drumstick weights, and lighter tibia weights. Males on the HISU lighting programme from 15 to 19 weeks of age had larger testes; however, after 20 weeks of age they were larger in males on the LISD lighting regimen. Cleaning and disinfecting the drinking troughs daily rather than weekly had no effect on any production variable measured.

Animals↗
PubMed1986

Growth, feed conversions, and yields of turkey parts of three strains of hen turkeys as influenced by age.

Effects of age on the growth, feed to gain ratios, individual part weights, and yields of hen turkeys were determined weekly from ages 12 to 21 weeks. Two hundred birds from each of three strains (A, B, and C) were processed. All three strains of hen turkeys continued to gain weight throughout the study. During the 12 to 21-week-old period birds grew from an average of 4.76 kg to 9.17 kg, while the cumulative feed to gain ratios went from 1.97 to 2.94. Strain B consistently weighed more than Strains A and C for the duration of the study. Weights of all parts increased as hens grew larger. However, the parts' proportion of total weight changed. Percentages of breast, breast muscle, and fat increase, while percentages of wing, drumstick, and skin decreased. Breast, breast muscle, and fat yields increased from 32.8 to 35.9%, 23.8 to 28.0%, and 1.7 to 5.1%, respectively. Both wing and drumstick percentages declined from approximately 14.0 to 12.0%. Thigh, thigh muscle, and shell percentages varied, but ended near their starting levels, of 14.8, 10.5, and 21.8%, respectively. At 21 weeks of age the hen turkeys were still gaining body weight. Breast weight--both actual and percentages--were still increasing.

Aging↗
PubMed1985

Stable inheritance of plasmid R1 requires two different loci.

The largest EcoRI fragment from plasmid R1 mediates a stability phenotype which is required to ensure the stable inheritance of this low-copy-number plasmid. When covalently linked to small, unstable R1 derivatives, this fragment makes the plasmids as stable as the wild-type R1 plasmid. A genetic analysis showed that two independently acting stabilization functions are encoded by this EcoRI fragment, both of which have the potential of partial stabilization of mini-R1 plasmids. The two loci are located at opposite ends of the fragment. Stabilization was also obtained by inserting these regions in unrelated, unstable plasmids from the p15 group. One of the two functions was very efficient in stabilizing such foreign replicons. Besides the stability phenotype, these genes exert incompatibility in an allele-specific manner. The stability functions do not seem to interfere seriously with the copy number of the plasmid.

Cloning, Molecular↗
PubMed1985

A randomized trial of iohexol versus amidotrizoate in endoscopic retrograde pancreatography.

To evaluate whether a low-osmolar contrast medium could decrease hyperamylasemia after endoscopic retrograde pancreatography, a prospective randomized double-blind trial of 54 consecutive patients with suspected pancreatic disease referred for endoscopic retrograde pancreatography was performed. The low-osmolar contrast medium iohexol and high-osmolar amidotrizoate were used. No statistically significant differences with regard to rise in pancreatic-type amylase, pain reaction, or diagnostic information were found. No case of acute pancreatitis was observed.

Adult↗
PubMed1984

Low-copy-number plasmid-cloning vectors amplifiable by derepression of an inserted foreign promoter.

By insertion of a DNA fragment, containing the phage lambda pR promoter and the pM-promoted cI857 allele of the lambda repressor gene, in plasmid R1 upstream of the replication control genes, cloning vectors have been constructed which are present in one copy per chromosome at temperatures below 37 degrees C, and which display uncontrolled replication at 42 degrees C. Derivatives have been made which carry the R1 par region, stabilizing the plasmid at low temperature when grown in the absence of selection pressure. Cells harbouring these plasmids stop growing after 1-2 h incubation at 42 degrees C, and at this time 50% of the total DNA in the cells is plasmid DNA corresponding to more than 1000 plasmid molecules per cell. Concomitant with plasmid amplification at the high temperature, synthesis of plasmid-coded gene products is amplified, and these vectors can therefore be utilized for obtaining greatly enhanced yields of gene products that may be detrimental to the host cell when present in large amounts.

DNA Replication↗
PubMedDate not supplied

Long-range cooperativity between gene regulatory sequences in a prokaryote.

Regulation of transcription initiation by proteins binding at DNA sequences some distance from the promoter region itself seems to be a general phenomenon in both eukaryotes and prokaryotes. Proteins bound to an enhancer site in eukaryotes can turn on a distant gene, whereas efficient repression of some prokaryotic genes such as the gal, ara and deo operons of Escherichia coli, requires the presence of two operator sites, separated by 110, 200 and 600 base pairs (bp) respectively. In the deo operon, which encodes nucleoside catabolizing enzymes, we have shown that efficient and cooperative repression can be obtained when the distance between the two sites ranges from 224 to 997 bp. Here, we report that transcription initiation can be regulated from an operator site placed 1 to 5 kilobases (kb) downstream of the deoP2 promoter (and downstream of the transcribed gene), and present the first experimental data for prokaryotic regulation at distances greater than 1 kb. Our results support the model of DNA loop formation as a common regulatory mechanism explaining both some prokaryotic regulation and the action of eukaryotic enhancers.

Cells↗