A single base mutation in the gene for type III collagen (COL3A1) converts glycine 847 to glutamic acid in a family with Ehlers-Danlos syndrome type IV. An unaffected family member is mosaic for the mutation

Summary Ehlers-Danlos syndrome type IV, an inherited connective tissue disease, is usually caused by mutations in the gene for type III collagen. Here, we describe a glycine to glutamic acid substitution in a patient with this syndrome. Previous studies had shown that fibroblasts from the patient, his mother and brother secreted a reduced amount of type III collagen and also produced an overmodified form of the protein that was preferentially retained intracellularly. Peptide mapping experiments indicated that the mutation was located within cyanogen bromide peptide 9. This was supported by chemical cleavage analysis and sequencing of cDNA encoding this region. Allele-specific oligonucleotide hybridisation of genomic DNA confirmed that a G to A mutation converted Gly 847 to Glu. The mutation was present in two other affected family members and also in a third, who was clinically unaffected. Further analysis of this unaffected individual revealed reduced mutant:normal ratios in DNA obtained from both blood and hair samples, showing that she was mosaic for the mutation.     

Demographic responses of arctic hares Lepus arcticus placed on two predominantly forested islands in Newfoundland

During January-April 1989. we monitored survival, reproduction, and body condition of 19 radio-collared arctic hares Lepus areticus introduced to two predominantly (80%) forested islands. Merchant (66 1 ha) and Burke (82 6 ha), in Placentia Bay, Newfoundland By late April, bone-marrow fat (42 7%) and kidney fat indices were lower than found in populations on the mountain barrens of western Newfoundland However, most island hares gained weight overwinter, and litter sizes (mean. 4 2 in utero) and testis weights (mean, 8 3 g) were as large or larger than recorded from other introduced and natural populations in Newfoundland The distribution of telemetry locations, tracks and feeding sites indicated that hares frequented the scattered barrens (totalling c 30 ha) on both islands in greater proportion than available These results suggest that, in the absence of snowshoe hares and mammalian predators, forested regions interspersed with small patches of barrens can sustain arctic hares     

Evidence of abortive recombination in ruv mutants of Escherichia coli K12

Summary Genetic recombination in Escherichia coli was investigated by measuring the effect of mutations in ruv and rec genes on F-prime transfer and mobilization of nonconjugative plasmids. Mutation of ruv was found to reduce the recovery of F-prime transconjugants in crosses with recB recC sbcA strains by about 30-fold and with recB recC sbcB sbcC strains by more than 300-fold. Conjugative plasmids lacking any significant homology with the chromosome were transferred normally to these ruv mutants. Mobilization of the plasmid cloning vectors pHSG415, pBR322, pACYC184 and pUC18 were reduced by 20- to 100-fold in crosses with ruv rec ⁺ sbc ⁺ strains, depending on the plasmid used. Recombinant plasmids carrying ruv ⁺ were transferred efficiently. With both F-prime transfer and F-prime cointegrate mobilization, the effect of ruv was suppressed by inactivating recA. It is proposed that the failure to recover transconjugants in ruv recA ⁺strains is due to abortive recombination and that the ruv genes define activities which function late in recombination to help convert recombination intermediates into viable products.     

Hydrotropism and Its Interaction with Gravitropism in Maize Roots

We have partially characterized root hydrotropism and its interaction with gravitropism in maize (Zea mays L.). Roots of Golden Cross Bantam 70, which require light for orthogravitropism, showed positive hydrotropism; bending upward when placed horizontally below a hydrostimulant (moist cheesecloth) in 85% relative humidity (RH) and in total darkness. However, the light-exposed roots of Golden Cross Bantam 70 or roots of a normal maize cultivar, Burpee Snow Cross, showed positive gravitropism under the same conditions; bending downward when placed horizontally below the hydrostimulant in 85% RH. Light-exposed roots of Golden Cross Bantam 70 placed at 70° below the horizontal plane responded positively hydrotropically, but gravitropism overcame the hydrotropism when the roots were placed at 45° below the horizontal. Roots placed vertically with the tip down in 85% RH bent to the side toward the hydrostimulant in both cultivars, and light conditions did not affect the response. Such vertical roots did not respond when the humidity was maintained near saturation. These results suggest that hydrotropic and gravitropic responses interact with one another depending on the intensity of one or both factors. Removal of the approximately 1.5 millimeter root tip blocked both hydrotropic and gravitropic responses in the two cultivars. However, removal of visible root tip mucilage did not affect hydrotropism or gravitropism in either cultivar.     

Normal mouse strains differ in the site of initiation of closure of the cranial neural tube

The scanning electron microscopic study of day 9 embryos reported here documents differences among normal mouse strains in morphology of cranial neural tube closure. The site of initiation of contact and fusion of the cranial neural folds, previously defined as Closure 2 (Macdonald et al., '89), is located in the region of the junction between the forebrain (prosencephalon) and midbrain (mesencephalon) in three normal strains: LM/Bc, AEJ/RkBc, and ICR/Bc. However in a fourth normal strain, SWV/Bc, Closure 2 is initiated much further rostral, in the prosencephalic region. In addition, the anterior neuropore, rostral to Closure 2, closes late in ICR/Bc embryos, relative to the posterior progress of development of the Closure 2 seam. Initiation of closure from the most rostral end of the neural tube (Closure 3) appears to be relatively delayed in ICR/Bc embryos. We hypothesize that the observed genetic polymorphism in location of the first site of fusion between the cranial neural folds in normal mouse embryos may be one basis for differences among normal strains in liability to exencephaly induced by teratogens.     

Studies of the effect of retinoic acid on anterior neural tube closure in mice genetically liable to exencephaly

Previously we have shown that all SELH/Bc mouse embryos close their anterior neural tubes by an abnormal mechanism and that 10-20% of SELH/Bc embryos are exencephalic. The purposes of these studies were (1) to observe the effects of retinoic acid on the frequency of exencephaly in SELH/Bc embryos; (2) to compare the SELH/Bc response with those of normal strains and of other neural tube mutants; and (3) to compare, between SELH/Bc and a normal strain (SWV/Bc), the effects of retinoic acid on morphology of the closing anterior neural tube. SELH/Bc was more liable to retinoic acid-induced exencephaly than were normal strains. After maternal treatment with 5 mg/kg retinoic acid on day 8.5 of gestation, 53% of SELH/Bc embryos had exencephaly, compared with 22% in ICR/Bc and 14% in SWV/Bc. When these results were transformed according to the assumptions of the developmental threshold model, the effects of genotype and retinoic acid appeared to be additive. Similar treatment on day 9 or 10 of gestation had little or no effect on the frequency of exencephaly in SELH/Bc mice. These results are similar to the reported responses of the curly-tail and Splotch mutants, where frequencies of spina bifida but not exencephaly were decreased. This pattern suggests that studies of effects of periconceptional vitamin treatment on risk of human neural tube defects should consider anencephaly and spina bifida separately. The study comparing the morphology of anterior neural tube closure in SELH/Bc and normal SWV/Bc embryos showed that retinoic acid delays the elevation of the mesencephalic neural folds. This results in a "stalling" of many embryos in the first steps of neural tube closure, with their neural folds remaining convex and splayed wide apart. The delay in fold elevation was superimposed on the different closure patterns of the two strains. The overall conclusion is that there is no nonadditive interaction in the parameters studied between retinoic acid treatment and the SELH/Bc genotype.     

Influence of mefluidide on growth,development, and cell wall digestibility of sorghum

Application of mefluidide (N-[2,4-dimethyl-5-([(trifluoromethyl)sulfonyl]amino) phenyl]acetamide) inhibits plant development in perennial grasses. This study examined the effect of mefluidide on the morphological development and digestibility of sorghum. In the greenhouse, 5.9 × 10^–5 g active ingredient (a.i.) plant^–1 applied at the seedling, eight-leaf and boot stages reduced mean plant height 70%, 59%, and 2%, respectively. Heights were also reduced 14%, 15% and 35% by 5.9 × 10^–8, 5.9 × 10^–7 and 5.9 × 10^–6 gram a.i. plant^–1 applied at the eight-leaf stage. Field application of 0.26 or 0.52 kg ha^–1 mefluidide at either the eight-leaf or flagleaf stage reduced mean plant height of all cultivars. Basal tiller numbers increased 319% 28 d, and dry matter production was reduced 65% 42 d following mefluidide application at the eight-leaf stage. Treated stems were 34% higher and treated leaves were 7% higher in cellulase dry matter digestibility than control plants following mefluidide application at the eight-leaf stage. These results indicate that mefluidide application to vegetative stages in sorghum may enhance the forage value of the plants while it inhibits normal plant growth.     

Stimulated indole alkaloid release from Catharanthus roseus immobilized cultures. Initial studies.

Vacuolar sequestration of valuable secondary metabolites remains the major limitation to the use of immobilization technology for large scale plant-cell-based bioprocesses, which otherwise may be a more efficient culture system than suspension for this biomass. In this initial study, the release of indole alkaloids produced by immobilized Catharanthus roseus cells cultured in Zenk's Alkaloid Production Medium was evaluated. Unstimulated alkaloid release in immobilized cultures reached levels of 10 to 50% of total production or 3 to 100% of known alkaloid content (30 to 4700 micrograms l-1), which was higher than that found for suspension cultures of the cell line used (10 to 25% of total production) without apparent cell lysis. Modifications of the medium pH value of immobilized cultures were explored in order to improve this release. Periodical additions of acid (HCl 0.1 N) or base (KOH 0.1 N) solutions (2% v/v) to different cultures resulted in rapid (less than 3 h) and transient variations in extracellular pH value from 5.5 to 4.3, and 5.8 to 8.5, respectively. In both cases, these variations provoked significant increase in total alkaloid (from approximately 5-10 mg l-1 to 15 mg l-1), ajmalicine (from 0 to approximately 0.29 mg l-1) and serpentine (from 0 to approximately 0.20 mg l-1) release, without apparent cell lysis or decrease in the culture viability. This product release was estimated to represent 100% of alkaloids produced.