Viability and dormancy of the Clematis vitalba aerial seed bank

Old man's beard (Clematis vitalba L.) is a liana species that has become invasive in many areas of its introduced range. Seeds are produced in abundance and are both physiologically and morphologically dormant upon maturity. To understand the importance of seeds to its invasiveness, changes in viability and dormancy of the aerial seed bank were tracked throughout the after-ripening period and during storage. Seeds collected every second month for 2 years were subjected to germination tests. Other seeds stored in outdoor ambient conditions or in a dry, chilled state were dissected before, during, and after imbibition, as well as during incubation, to measure embryo size. Less than 72% of seeds on the mother plant were viable. Viable seeds remained completely morpho-physiologically dormant throughout autumn, even when treated with nitrate. Physiological dormancy declined in response to seasonal changes, yet morphological dormancy did not change until seeds had been exposed to appropriate germination conditions for several days. Fully dormant autumn seeds decayed at higher rates during incubation than partially or fully after-ripened seeds, which were also more germinable and less dormant. Furthermore, seeds incubated in complete darkness were more likely to decay or remain dormant than those exposed to light. This study demonstrates that fewer than three-quarters of seeds produced are viable and further decay occurs after dispersal, yet total fertility is still very high, with enormous propagule pressure from seeds alone. Viable seeds are protected with two forms of dormancy; morphological dormancy requires additional germination cues in order to break after seasonal changes break physiological dormancy.

Breeding systems in Cyrtanthus (Amaryllidaceae): variation in self-sterility and potential for ovule discounting

Breeding systems of plants determine their reliance on pollinators and ability to produce seeds following self-pollination. Self-sterility, where ovules that are penetrated by self-pollen tubes that do not develop into seeds, is usually considered to represent either a system of late-acting self-incompatibility or strong early inbreeding depression. Importantly, it can lead to impaired female function through ovule or seed discounting when stigmas receive mixtures of self and cross pollen, unless cross pollen is able to reach the ovary ahead of self pollen ('prepotency'). Self-sterility associated with ovule penetration by self-pollen tubes appears to be widespread among the Amaryllidaceae. We tested for self-sterility in three Cyrtanthus species - C. contractus, C. ventricosus and C. mackenii - by means of controlled hand-pollination experiments. To determine the growth rates and frequency of ovule penetration by self- versus cross-pollen tubes, we used fluorescence microscopy to examine flowers of C. contractus harvested 24, 48 and 72 h after pollination, in conjunction with a novel method of processing these images digitally. To test the potential for ovule discounting (loss of cross-fertilisation opportunities when ovules are disabled by self-pollination), we pollinated flowers of C. contractus and C. mackenii with mixtures of self- and cross pollen. We recorded full self-sterility for C. contractus and C. ventricosus, and partial self-sterility for C. mackenii. In C. contractus, we found no differences in the growth rates of self- and cross-pollen tubes, nor in the proportions of ovules penetrated by self- and cross-pollen tubes. In this species, seed set was depressed (relative to cross-pollinated controls) when flowers received a mixture of self and cross pollen, but this was not the case for C. mackenii. These results reveal variation in breeding systems among Cyrtanthus species and highlight the potential for gender conflict in self-sterile species in which ovules are penetrated and disabled by pollen tubes from self pollen.

Where have all the blue flowers gone: pollinator responses and selection on flower colour in New Zealand Wahlenbergia albomarginata

Although pollinators are thought to select on flower colour, few studies have experimentally decoupled effects of colour from correlated traits on pollinator visitation and pollen transfer. We combined selection analysis and phenotypic manipulations to measure the effect of petal colour on visitation and pollen export at two spatial scales in Wahlenbergia albomarginata. This species is representative of many New Zealand alpine herbs that have secondarily evolved white or pale flowers. The major pollinators, solitary bees, exerted phenotypic selection on flower size but not colour, quantified by bee vision. When presented with manipulated flowers, bees visited flowers painted blue to resemble a congener over white flowers in large, but not small, experimental arrays. Pollen export was higher for blue flowers in large arrays. Pollinator preference does not explain the pale colouration of W. albomarginata, as commonly hypothesized. Absence of bright blue could be driven instead by indirect selection of correlated characters.

Two new pathogenic ascomycetes in Guignardia and Rosenscheldiella on New Zealand's pygmy mistletoes (Korthalsella: Viscaceae)

Two new pathogens, Guignardia korthalsellae and Rosenscheldiella korthalsellae, are described from New Zealand's pygmy mistletoes (Korthalsella, Viscaceae). Both form ascomata on living phylloclades with minimal disruption of the tissue. Fungal hyphae within the phylloclade are primarily intercellular. Guignardia korthalsellae disrupts a limited number of epidermal cells immediately around the erumpent ascoma, while the ascomata of Rosenscheldiellakorthalsellae develop externally on small patches of stromatic tissue that form above stomatal cavities. Rosenscheldiella is applied in a purely morphological sense. LSU sequences show that R. korthalsellae as well as another New Zealand species, Rosenscheldiella brachyglottidis, are members of the Mycosphaerellaceaesensu stricto. Genetically, Rosenscheldiella, in the sense we are using it, is polyphyletic; LSU and ITS sequences place the two New Zealand species in different clades within the Mycosphaerellaceae. Rosenscheldiella is retained for these fungi until generic relationships within the family are resolved. Whether or not the type species of Rosenscheldiella, R. styracis, is also a member of the Mycosphaerellaceae is not known, but it has a similar morphology and relationship to its host as the two New Zealand species.

A case report of massive vulvar edema during tocolysis of preterm labor

Bilateral vulvar edema that is not associated with preeclampsia has been reported only rarely during pregnancy or the puerperium. A primiparous patient in premature labor at 34 weeks' gestation with no history of lymphatic or venous obstruction underwent combination tocolysis with intravenous ritodrine and magnesium sulfate. On the fifth day of tocolysis, edema developed in the right labium majus pudendi and gradually spread to the left labia during the ensuing 24 hours. The patient remained afebrile, normotensive, and without signs of localized infection or anasarca. A trial of triple intravenous antibiotics and local skin care proved ineffective. By the ninth hospital day, the edema and discomfort had progressed, thereby precluding vaginal examination without sedation. In spite of progressive cervical dilatation with tocolysis, cesarean delivery was performed. With no further treatment, the vulvar edema gradually resolved during the next week.

The nitrite and leukocyte esterase tests for the evaluation of asymptomatic bacteriuria in obstetric patients

The purpose of this investigation was to compare the reliability of a urine dipstick evaluation for nitrites and leukocyte esterase activity with that of a urine culture in diagnosing asymptomatic bacteriuria in obstetric patients. A clean-catch midstream urine specimen was obtained from 750 consecutive obstetric patients presenting for initial evaluation. One portion of the specimen was tested for nitrites and leukocyte esterase activity with Chemstrip LN dipsticks. A second aliquot of urine was plated on blood and MacConkey agar and incubated aerobically. The cost of the nitrite and leukocyte esterase test was $0.35. The per patient charge for the urine cultures would have been $28. Sixty-two women (8.3%) had urine cultures of 100,000 or more colony-forming units of a uropathogen per milliliter. The sensitivities of the nitrite and leukocyte esterase test in identifying patients with positive cultures were 43 and 77%, respectively, and the specificities were 99 and 96%, respectively. The sensitivity and specificity for the two tests combined (either test abnormal) were 92 and 95%, respectively. Five patients had negative screening tests but positive urine cultures; all five isolates were gram-positive organisms, three group B streptococci and two enterococci. We conclude that neither the nitrite test nor the leukocyte esterase test alone is a sensitive enough screening test to detect asymptomatic bacteriuria in obstetric patients. The combination of the two tests, however, may provide an acceptable cost-effective alternative to screening all asymptomatic obstetric patients with urine cultures.

External cephalic version at term: is a tocolytic necessary?

This prospective investigation evaluates the benefit of a beta-mimetic tocolytic for external cephalic version. From July 1, 1984 to May 15, 1987, 58 patients who had breech presentations between 37-41 weeks' gestation were considered for external cephalic version. The patients were randomly assigned to one of two groups: tocolytic or no tocolytic. An ultrasound examination, serum alpha-fetoprotein (AFP), Kleihauer-Betke test, and nonstress test (NST) were performed before and after the attempt at version. A version was not attempted if there was evidence of intrauterine growth retardation (IUGR), oligohydramnios, or a nonreactive NST. Patients in the tocolytic group received 200 micrograms/minute of ritodrine hydrochloride for 20 minutes via continuous intravenous infusion before a version was attempted. Twenty of the 30 patients (66.7%) in the tocolytic group and 19 of the 28 patients (67.8%) in the no-tocolytic group had successful versions, a nonsignificant difference. The nine patients with unsuccessful version attempts in the group without a tocolytic then received intravenous ritodrine and underwent a second attempt. Only one of these nine attempts was successful. There were no serious maternal or fetal complications associated with the attempts at version. In our patient population, use of a tocolytic did not significantly increase the probability of a successful version.

Single-dose cefazolin versus cefonicid for antibiotic prophylaxis in cesarean delivery

The purpose of this prospective investigation was to compare a single intravenous dose of cefazolin to a single dose of cefonicid as prophylaxis for women having unscheduled cesarean delivery. In a double-blind, randomized design, 96 patients were assigned to receive a 1-g dose of cefazolin and 103 patients were designated to receive a 1-g dose of cefonicid. The antibiotics were administered after delivery of the infant. The two groups were comparable with respect to recognized risk factors for postcesarean infection. There were no statistically significant differences between the groups in the incidence of standard febrile morbidity, endomyometritis, urinary tract infection, wound infection, and bacteremia. There were also no significant differences between the groups in the fever index or the duration of hospitalization. We conclude that cefazolin and cefonicid provide a similar degree of prophylaxis against infection in patients having unscheduled cesarean delivery.