Vitellogenin and ecdysteroid titers in Ixodes scapularis during vitellogenesis

Ecdysteroids are the only hormones unequivocally identified thus far in ticks. We found a positive correlation between ecdysteroid concentration and vitellogenin synthesis in female Ixodes scapularis. Vitellogenin (Vg) synthetic activity was measured by an in vitro assay for Vg, involving incubations of the fat body with 35S-methionine and immunoprecipitation collected on a solid-phase matrix, protein A. Vitellogenin synthetic activity in the fat body was undetectable in unfed females but was detected after tick attachment to the host. Vitellogenin production in the fat body remained low from attachment until 2 days prior to detachment from the host. Vitellogenin synthesis in the fat body peaked 2 days after detachment and declined to a level 2-3 times above background from 6 days after dropping from the host through oviposition. A peak of ecdysteroids in females 6 days after attachment preceded an increasing rate of Vg synthesis, suggesting a positive correlation between these parameters. Ecdysone and 20-hydroxyecdysone, the 2 major ecdysteroids present during vitellogenesis, could not be detected in females prior to feeding or 2 days after attachment to the host; however, concentrations began to increase 4 days after attachment, peaked during rapid engorgement, and subsequently declined.

Purification and partial characterization of vitellin from the black-legged tick, Ixodes scapularis

Vitellin from the black-legged tick, Ixodes scapularis, was purified from eggs using gel filtration and ion exchange chromatography. The purified protein had a native molecular mass of 480 kDa. Under reducing conditions (sodium dodecyl sulfate-polyacrylamide gel electrophoresis; SDS-PAGE), vitellin was composed of seven polypeptides each at 154, 135, 87, 78, 67, 64 and 35 kDa. The isoelectric point was pH 6.9 and absorption maxima for the yolk protein were 280 and 400 nm. As in other ticks, vitellin from I. scapularis is also a hemoglycolipoprotein. Carbohydrates detected in vitellin were predominantly mannose with a small amount of N-acetylglucosamine. Lipids detected by thin layer chromatography (TLC) were triglycerides, free fatty acids, and cholesterol. Phospholipids associated with vitellin were phosphatidylethanolamine and phosphatidylcholine. Polyclonal serum produced in rabbits recognized vitellin from the eggs and ovaries, and vitellogenin from the hemolymph and fat body in reproductive females. This is the first report on the characterization of yolk proteins from a prostriate tick.

The effect on mitochondrial function of the tRNA Ser(UCN)/COI A7445G mtDNA point mutation associated with maternally-inherited sensorineural deafness

An A to G point mutation at nucleotide position 7445 in the mitochondrial DNA genome is associated with maternally-inherited sensorineural deafness in two separate human pedigrees. To determine whether this point mutation [tRNA(SER)UCN)/COI A7445G] led to sensorineural deafness by affecting cellular energy metabolism we investigated the bioenergetic function of mitochondria in lymphoblastoid cultures established from these patients. Even though essentially all of the mitochondrial DNA in these cells contained the mutation at nucleotide position 7445, there was no effect on a number of mitochondrial bioenergetic functions (mitochondrial content, membrane potential in both intact and digitonin-permeabilised cells, cellular ATP/ADP ratios and respiratory enzyme activity) when compared with control cells. The implications of these findings for both the aetiology of the sensorineural deafness associated with the A7445G mtDNA mutation, and the role of bioenergetic defects in mitochondrial DNA diseases in general are discussed.

Unusual strain of Borrelia burgdorferi isolated from Ixodes dentatus in central Georgia

A new, unusual spirochete was cultured in Barbour-Stoenner-Kelly (BSK II) medium from the midgut and other tissues of the tick Ixodes dentatus. The tick was collected from leaf litter in an oak-pine wood lot in Bibb County approximately 7.2 km from Macon in central Georgia during February 1993. Characterization by indirect immunofluorescence using 5 murine monoclonal antibodies, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of whole spirochetal lysates, and by polymerase chain reaction assay for several known DNA target sequences indicates that the spirochete is Borrelia burgdorferi sensu lato. It is genetically different from the B-31 reference strain of B. burgdorferi sensu stricto that is typical of strains causing Lyme borreliosis in North America. Range of infectivity and pathogenesis of the Bibb County isolate (BC-1) are unknown but being investigated. The BC-1 strain is the first B. burgdorferi isolate from I. dentatus in the southeastern United States (I. dentatus is not the common vector for Lyme borreliosis in humans). Additionally, the collection site was approximately 322 km from the Atlantic coast, far distant from where most B. burgdorferi isolates have been obtained.

Vitellogenin concentrations in the haemolymph and ovaries of Ixodes scapularis ticks during vitellogenesis

The vitellogenin and vitellin concentrations in the haemolymph and ovaries of Ixodes scapularis females were determined using a double sandwich enzyme-linked immunosorbent assay. The level of vitellogenin in the haemolymph began to increase just prior to tick detachment from the host and continued to increase until 2 days after detachment. There was a slight decrease in the vitellogenin level 4 days after detachment, but a second peak was observed approximately 5 days after oviposition. Subsequent to oviposition, the vitellogenin levels in the haemolymph quickly decreased. The concentration of vitellogenin in the haemolymph ranged from 1.55 to 11.48 micrograms microliters-1 during the period after dropping from the host through oviposition. The concentration of vitellin in the ovaries began to increase as the female began rapid engorgement (0.03 mg per female) and declined after oviposition (0.1 mg per female).

Altered mitochondrial function in fibroblasts containing MELAS or MERRF mitochondrial DNA mutations

A number of human diseases are caused by inherited mitochondrial DNA mutations. Two of these diseases, MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) and MERRF (myoclonic epilepsy and ragged-red fibres), are commonly caused by point mutations to tRNA genes encoded by mitochondrial DNA. Here we report on how these mutations affect mitochondrial function in primary fibroblast cultures established from a MELAS patient containing an A to G mutation at nucleotide 3243 in the tRNA(Leu(UUR) gene and a MERRF patient containing an A to G mutation at nucleotide 8344 in the tRNA(Lys) gene. Both mitochondrial membrane potential and respiration rate were significantly decreased in digitonin-permeabilized MELAS and MERRF fibroblasts respiring on glutamate/malate. A similar decrease in mitochondrial membrane potential was found in intact MELAS and MERRF fibroblasts. The mitochondrial content of these cells, estimated by stereological analysis of electron micrographs and from measurement of mitochondrial marker enzymes, was similar in control, MELAS and MERRF cells. Therefore, in cultured fibroblasts, mutation of mitochondrial tRNA genes leads to assembly of bioenergetically incompetent mitochondria, not to an alteration in their amount. However, the cell volume occupied by secondary lysosomes and residual bodies in the MELAS and MERRF cells was greater than in control cells, suggesting increased mitochondrial degradation in these cells. In addition, fibroblasts containing mitochondrial DNA mutations were 3-4-fold larger than control fibroblasts. The implications of these findings for the pathology of mitochondrial diseases are discussed.

Natural occurrence and characterization of the Lyme disease spirochete, Borrelia burgdorferi, in cotton rats (Sigmodon hispidus) from Georgia and Florida

This is the first report of natural infection by Borrelia burgdorferi in the cotton rat Sigmodon hispidus. Nine B. burgdorferi isolates were obtained from ear tissues, urinary bladders, or both, by culturing tissues in BSKII medium. The rat from which the SI-3 isolate was cultured was from the same site (Sapelo Island, Georgia) as an infected cotton mouse Peromyscus gossypinus and Ixodes scapularis tick reported previously. The 8 B. burgdorferi isolates from rats in Florida included 1 (AI-1) from Amelia Island, 1 (FD-1) from Faver-Dykes State Park, and 6 (MI-3 through MI-8) from Merritt Island. The distance between Sapelo Island and Merritt Island is approximately 400 km. All B. burgdorferi isolates were characterized by indirect immunofluorescence using monoclonal antibodies to OspA (H3TS, H5332) and OspB (H5TS, H6831), polymerase chain reaction detection of specific B. burgdorferi B-31 DNA target sequences (ospA, fla, and a random chromosomal sequence), and sodium dodecyl sulfate-polyacrylamide gel electrophoresis of spirochetal proteins. The phenotypic and genotypic characteristics of the isolates are discussed, as well as the probable importance of the cotton rat as a reservoir for B. burgdorferi in the southern United States.

Reaction of human chymase with reactive site variants of alpha 1-antichymotrypsin. Modulation of inhibitor versus substrate properties

Inhibition of human chymase by alpha 1-antichymotrypsin produces 3.5 mol of degraded inhibitor for every mol of chymase inhibited, resulting in a stoichiometry of inhibition (SI) of 4.5. In the present study, the substrate versus inhibitor properties of this reaction were examined further using wild type and mutant recombinant antichymotrypsins (rACT). Titration of chymase hydrolytic activity with rACT-L358 (wild type) and reactive site (P1) variants of ACT, L358W, L358M, and L358F revealed that the SI was sensitive to P1 residue replacements. SI values increased in the order of Trp < Met < Leu < Phe where SI values were 1.5, 2, 4, and 7, respectively. Chymase inhibitor complex and cleaved inhibitor were demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis for all variants; the relative intensities of each band were consistent with SI values established by titration. NH2-terminal sequence analyses of the products formed in the reaction of chymase with rACT-L358F indicated that the P1-P1' bond was the primary site of cleavage resulting in the hydrolysis and inactivation of this variant. The apparent second-order rate constant for chymase inhibition (k'/[I]) by rACT also was affected by P1 substitution. k'/[I] values increased in an order opposite that obtained for SI values (Phe < Leu < Met < Trp). The reactive loop mutant (rACT-P3P3') produced by replacing the reactive site region of ACT (Thr356-Val361) with that of alpha 1-proteinase inhibitor (Ile356-Pro361) revealed a different reaction pattern. Although its SI was near 1, the value for k'/[I] was the lowest among variants. rACT-L358R, another P1 variant, did not inhibit chymase. These results are evaluated with respect to the substrate preferences of human chymase and with respect to partitioning schemes proposed to explain SI values greater than 1.

Developmental and gender differences in the relationship of behavior pattern to heart rate reactivity between two teenage samples

The Type A Behavior Pattern was assessed for 122 teenagers from two age-groups. Subjects had their heart rate measured during rest and presentation of a mental arithmetic stressor under timed and competitive conditions. Data were analyzed to determine whether sex, age, task performance, and behavior pattern predicted the degree of heart rate reactivity shown by these children. Although there were no significant main effects for behavior pattern, sex, or age, there was a significant interaction among age, sex, and behavior pattern. It is suggested that the two age groups of teenagers sampled here differ in the relationships they show between behavior pattern and heart rate reactivity. This result challenges some previous assumptions with regard to the homogeneity of teenagers on this issue.

Isolation and transmission of the Lyme disease spirochete from the southeastern United States

The isolation of the Lyme disease spirochete (Borrelia burgdorferi) from the southeastern United States is reported. Three isolates, two from cotton mice (Peromyscus gossypinus) and one from the black-legged tick (Ixodes scapularis), were recovered from Sapelo Island, Georgia, in July and September 1991. The spirochetes were characterized by indirect fluorescent antibody assay using a battery of five monoclonal antibodies, by sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS/PAGE) of whole cell lysates, and by the polymerase chain reaction (PCR) assay using primers for three DNA target sequences found in B. burgdorferi reference strain B-31. Transmission experiments indicate that the three Georgia isolates can infect experimentally inoculated hamsters and mice. Tick transmission of one of the isolates has been attempted so far; I. scapularis transmitted isolate SI-1 from hamsters to mice, but the lone-star tick, Amblyomma americanum, did not.

Conspecificity of the ticks Ixodes scapularis and I. dammini (Acari: Ixodidae)

Reciprocal crosses between Ixodes dammini Spielman, Clifford, Piesman & Corwin from Massachusetts and Ixodes scapularis Say from Georgia produced offspring through the F3 generation when the experiment was discontinued. Reciprocal I. dammini x Ixodes pacificus Cooley & Kohls (California) and I. scapularis x I. pacificus crosses produced F1 progeny; however, all progeny were sterile. Assortative mating experiments between I. dammini and I. scapularis indicated that males and females of both species mated with the opposite sex of heterospecific or conspecific ticks when there was a choice. Conventional discriminant analysis of morphometric measurements of ticks from Georgia, North Carolina, Maryland, Massachusetts, and two populations of F1 hybrids indicated that there were recognizable differences. However, size-free (sheared) discriminant analysis indicated that these differences were largely size-dependent, with much overlap of the four eastern and two hybrid populations but no overlap with I. pacificus from California. Analysis of chromosomes (morphology and C band) indicated no differences between the Georgia and Massachusetts populations but showed a difference between them and the California population of I. pacificus. Analysis of isozymes showed that the genetic identity value for the Georgia and Massachusetts populations was within the normal range for conspecific populations, whereas the California population indicated congeneric but not conspecific relatedness to the Georgia and Massachusetts populations. Life cycle data collected under similar laboratory conditions showed no differences in length of feeding and molting periods among Georgia, Massachusetts, and California populations. These data and results of the work of other authors on tick host preferences and vector competence indicate that I. dammini is not a valid species separate from I. scapularis. Because the name Ixodes scapularis Say, 1821, has priority over the name Ixodes dammini Spielman, Clifford, Piesman & Corwin, 1979, I. dammini is relegated to a junior subjective synonym of I. scapularis (based on Article 23 of the International Code of Zoological Nomenclature).

cis-bis(pyridine)platinum(II) organoamides with unexpected growth inhibition properties and antitumor activity

The platinum(II) organoamides [Pt(NRCH2)2L2] (L = pyridine (py), R = p-HC6F4, C6F5,p-IC6F4,p-CIC6F4,p-C6F5C6F4; L = 4-methylpyridine, R = p-HC6F4) and [Pt(NRCH2CH2NR')(py)2] (R = p-HC6F4, R' = C6F5, p-BrC6F4, or p-MeC6F4) inhibit the growth of murine L1210 leukemia cells in culture with ID50 values for continuous exposure in the range 0.6-2.7 microM. Representative complexes are also active against L1210 cells in 2-h pulse exposures, as well as against the cisplatin-resistant variant L1210/DDP and human colonic carcinoma cell lines HT 29 and BE. Three complexes [Pt(NRCH2)2L2] (R = p-HC6F4, C6F5, or p-IC6F4) have good activity (T/C greater than or equal to 180%) against P388 leukemia in mice, and all other compounds tested are active except when R = p-C6F5C6F4, L = py. Although the molecular basis of the biological activity of these complexes is not known, the observation of good activity for amineplatinum(II) compounds with no hydrogen substituents on the nitrogen donor atoms introduces a new factor in the anticancer behavior of platinum(II) complexes.

4-(6'-Methoxy-3',4'-dihydronaphthalen-1'-yl)butan-2-one and the Derived Guareschi Imide

4-(6′-Methoxy-3′,4′-dihydronaphthalen-1′-yl)butan-2-one (6b) was condensed with ethyl cyano-acetate to give a mixture of the geometric isomers of the α, β unsaturated cyano ester (8), reaction of which with the anion derived from cyanoacetamide gave the Guareschi imide (7). Attempts to hydrolyse this to 3-[2′-(6″-methoxy-3″,4″-dihydronaphthalen-1″-yl)ethyl]-3-methylglutaric acid (4) gave only polymeric material. The preparations of 2,2-ethylenedioxy-4-(6′-methoxynaphthalen-1′-yl)butane (5a) and the corresponding butanone (5b) are also described.

Preparation of 2-(3-Bromo-1-methylpropyl)-1,3-dioxolan and the Corresponding Chloride From 2-Methylbutyrolactone

Lithium aluminium hydride reduction of ethyl 4-chloro-2-methylbutanoate (4a), derived from 3-methyldihydrofuran-2(3H)-one (2-methylbutyrolactone) (1), gave 4-chloro-2-methylbutan-1-ol (5a), oxidation of which with pyridinium chlorochromate afforded 4-chloro-2-methylbutanal (8a). The aldehyde (8a) was converted into 2-(3?-chloro-1′-methylpropyl)-1,3-dioxolan (7a) in 47% overall yield from (1). 2-(3′-Bromo-1′-methyIpropyl)-1,3-dioxolan (7b) was similarly obtained in 49% overall yield from (1). Attempted conversion of 3-methyltetrahydrofuran-2-ol (2) into the corresponding cyclic ethylene acetal gave epimeric mixtures of 2-(3′-methyltetrahydrofuran-2′-yloxy)ethanol (6) and 2,2′-ethylenedioxybis(3-methyltetrahydrofuran) (9).

Synthesis of 2-(5',5'-Ethylenedioxy-1'-methylcyclopent-2'-en-1'-yl)ethanol, and Some 2H-Cyclopenta[b]furan Derivatives Formed by Intramolecular Displacement Reactions

Exchange dioxolanation of 2-methyl-2-(prop-2′-enyl)cyclopentane-1,3-done (1b) gave 3,3- ethylenedioxy-2-methyl-2-(prop-2′-enyl) cyclopentan-1-one (2) which, upon reduction and esterification , afforded the epimeric 3,3-ethylenedioxy-2-methyl-2-(prop-2′-enyl) cyclopent-1-yl benzoates (6d). Oxidative cleavage of the terminal double bond in (6d),followed by sodium borohydride reduction yielded 3,3-ethylenedioxy-2-(2'-hydroxyethyl)-2-methylcyclopent-1-yl benzoate (4b) which underwent acid- catalysed rearrangement to 6a-(2′-hydroxyethoxy)-3a- methylhexahydrocyclopenta [b]furan-4-yl benzoate (8b). Flash vacuum pyrolysis of the t- butyldimethylsilyl ether (12), derived from the hydroxy acetal (4b), afforded 3-[2′- (t- butyldimethylsilyloxy )ethyl]-4,4-ethy1enedioxy-3-methylcyclopent-1-ene (14) which upon selective cleavage of the silyl ether group gave 2-(5′,5′-ethylenedioxy-1′-methylcyclopent- 2'′en-1′-y1)ethanol (7). Reaction of the mesylate (16) of (7) with lithium bromide or iodide in tetrahydrofuran at 50-55� for several hours yielded some of the corresponding 3-(2′-haloethyl) compounds (17), but gave mainly the rearranged 6a-(2′-haloethoxy)-3a-methyl-3,3a,6,6a-tetrahydro-2H-cyclopenta[b]furans (19a) and (19b). Some related chemistry is described.

Organization and evolution of repeated DNA sequences in closely related plant genomes

In common with many other eukaryotic species, the genomes of species in the genus Allium contain a high proportion of repeated DNA sequences, which may be implicated in the considerable differences in genome size that are seen between even very closely related species. The gross organization of repetitive sequences within the genome of Allium sativum and of some other related species has been investigated using DNA/DNA hybridization studies. Such studies show that there has been much modulation in the amounts of different repeated DNA families during the evolution of the genus Allium; these repetitive elements are interspersed in all species with sequences of low repetition. The organization and distribution of one particular repetitive family within the genus has been examined using a cloned hybridization probe. Hybridization of this probe to DNA from related genomes reveals that this element is present in all Allium species examined, but with large-scale modulation of its abundance, and some considerable changes in its sequence environment. The evolution of such genome-specific arrangements of common repetitive elements and the possible mechanisms by which they might be maintained are discussed.