Wide variation of winter-induced sustained thermal energy dissipation in conifers: a common-garden study.

Low temperature in winter depresses rates of photosynthesis, which, in evergreen plants, can exacerbate imbalances between light absorption and photochemical light use. Damage that could result from increased excess light absorption is minimized by the conversion of excitation energy to heat in a process known as energy dissipation, which involves the de-epoxidized carotenoids of the xanthophyll cycle. Overwintering evergreens employ sustained forms of energy dissipation observable even after lengthy periods of dark acclimation. Whereas most studies of photoprotective energy dissipation examine one or a small number of species; here, we measured the levels of sustained thermal energy dissipation of seventy conifer taxa growing outdoors under common-garden conditions at the Red Butte Garden in Salt Lake City, Utah, U.S.A. (forty nine taxa were also sampled for needle pigment content). We observed an extremely wide range of wintertime engagement of sustained energy dissipation; the percentage decrease in dark-acclimated photosystem II quantum efficiency from summer to winter ranged from 6 to 95%. Of the many pigment-based parameters measured, the magnitude of the seasonal decrease in quantum efficiency was most closely associated with the seasonal increase in zeaxanthin content expressed on a total chlorophyll basis, which explained only slightly more than one-third of the variation. We did not find evidence for a consistent wintertime decrease in needle chlorophyll content. Thus, the prevailing mechanism for winter decreases in solar-induced fluorescence emitted by evergreen forests may be decreases in fluorescence quantum yield, and wintertime deployment of sustained energy dissipation likely underlies this effect.

Characterization of White Rust of Perennial Pepperweed Caused by Albugo candida in California.

In California, perennial pepperweed (Lepidium latifolium) is an introduced Brassicaceae plant that is invasive, highly competitive, and listed as a noxious weed that grows in areas such as marshes, meadows, roadsides, and irrigation ditches. From 2008 through 2010, perennial pepperweed growing near farms in Monterey and Santa Clara counties was infected with white rust. Symptoms were light green-to-chlorotic spots on adaxial leaf surfaces and corresponding white, blister-like sori growing underneath the raised leaf epidermis on the abaxial surface. Sporangia were collected from lesions and used for DNA extraction. The internal transcribed spacer (ITS) region was amplified with primers ITS1/ITS4 and sequenced. The sequence matched with Albugo candida by BLAST against GenBank. On the basis of morphological and molecular data, the pathogen was confirmed to be A. candida. Pathogenicity was tested by scraping sporangia from infected leaves and spraying a suspension (1 × 105 sporangia/ml) onto pepperweed seedlings grown in pots. Plants were placed in an incubator at 100% relative humidity and 12°C for 48 h to induce zoospore release. Plants were subsequently maintained in a greenhouse. After 15 to 17 days, inoculated plants developed white rust symptoms and signs. Control plants sprayed with water did not become diseased. The experiment was completed two times with the same results. To determine the race of A. candida from perennial pepperweed, 4- to 5-week-old plants and 1- to 2-week-old seedlings of differential hosts (1-4) were inoculated in a similar fashion. The differential hosts were the following: Raphanus sativus (race 1), Brassica juncea cv. Burgonde (race 2A), B. juncea cv. Cutlass (race 2V), Armoracia rusticana (race 3), Capsella bursa-pastoris (race 4), Sisymbrium officinale (race 5), Rorippa islandica (race 6), B. rapa (B. campestris) cv. Torch (race 7A), B. rapa cvs. Reward, Cutlass, and AC Parkland (race 7V), B. nigra (race 8), B. oleracea (race 9), Sinapis alba (race 10), B. carinata (race 11), and perennial pepperweed as a control. White rust developed on pepperweed 10 to 14 days later but was not found on any of the differential hosts, indicating that this pathogen is not one of the currently described 11 races. The following commercial crop species were inoculated using the same method: arugula (Eruca sativa), Japanese mustard (B. campestris subsp. nipposinica), red mustard (B. juncea subsp. rugosa), tah tsai (B. campestris subsp. narinosa), cauliflower (B. oleracea subsp. botrytis), Chinese cabbage (B. campestris subsp. pekinensis), bok choy (B. rapa Chinensis group), broccoli raab (B. rapa subsp. rapa), and perennial pepperweed as a control. Only the perennial pepperweed developed white rust. To our knowledge, this is the first characterization of A. candida infecting perennial pepperweed in California. The disease has been documented on this plant in Colorado and also in Bulgaria, Portugal, and Spain. The host range information is important to growers because it indicates that the race currently infecting perennial pepperweed will not infect commercial crucifers. References: (1) P. A. Delwich and P. H. Williams. Cruciferae Newsl. 2:39, 1977. (2) C. B. Hill et al. Cruciferae Newsl. 13:112, 1988. (3) S. R. Rimmer et al. Can. J. Plant Pathol. 22:229, 2000. (4) P. R. Verma et al. Can. J. Bot. 53:1016, 1975.

Fluoride supplements and changes in tooth decay on the Island of Tristan da Cunha: 1966-1996.

BACKGROUND: The island of Tristan Da Cunha is one of the few examples in the world of a remote enclosed community. The inhabitants of the island were transported to England in 1961 as a result of a volcanic eruption and during their time in England they received a detailed dental health examination. They were later examined back on the island in 1966 by Dr John Fisher and in 1982 a school fluoride supplementation programme was introduced. AIM: The present paper reports the results of the first dental health survey to be carried out on the island since the introduction of a regular school fluoride supplementation programme in 1982. SUBJECTS AND METHODS: A cohort of 6-19-year-old subjects on the island were examined in 1996 using a similar protocol to that which was used by Fisher in the 1966 examination. RESULTS: Comparing the 6-12-year-olds who were caries free in 1966 with those caries free in 1996 using the Chi-squared statistic reveals a statistically significant greater number caries free in the more recent cohort (X2 - 6.0, P- 0.014). For the older age group (13-19 years), a similar comparison reveals a highly statistically significant difference(Z2 - 12.26, P 0.005). CONCLUSIONS: A significant increase in the number of caries free 6-19-year-old children in Tristan Da Cunha between 1966 and 1996 was noted: 1) This is a significant finding in the light of the school fluoride supplementation programme that was introduced on the island in 1982; and 2) Appropriate fluoride supplementation regimes may have conferred a protective effect in a group of children with a cariogenic diet. The paper discusses the significance of this study in the support of fluoridation as a method of reducing the prevalence of dental caries a nd also discusses possibilities for future research on the island of Tristan Da Cunha.

Islet cell antibodies in Sulawesi macaques.

Older monkeys of the Sulawesian species Macaca nigra spontaneously develop a lesion in the pancreatic islets of Langerhans in which there is deposition of amyloid and gradual degeneration of all cells, which can lead eventually to development of diabetes mellitus. Islet cell antibodies (ICA), formed in response to the release of cellular antigens, can be used to detect the islet lesion and to monitor the progression of each monkey toward diabetes. Numerous M. nigra and one M. tonkeana in captivity have been tested, but it is unknown whether the islet lesion occurs in monkeys in their natural habitat of Sulawesi. Blood samples collected from M. maurus, M. tonkeana, and hybrid M. maurus/tonkeana were assayed for ICA. When all monkeys were considered together, 33% had ICA positive against beta cells and 14% had ICA positive against alpha and/or D cells. Appearance of ICA in blood of males was virtually the same as in females. These results are similar to those found in M. nigra examined in captivity. Since all Sulawesian species share a common genetic heritage, these results would support the appearance of this lesion in their natural habitat. Cause(s) for formation of the lesion and eventual development of diabetes are unknown. There may be genetic factors or genetic predisposition to environmental factors. If environmental factors are responsible, then they must be present not only in the wild, but either carried with the monkeys or universally available, since M. nigra born in captivity also develop the lesion and diabetes after physical maturity at ca. 7+ years.

Anticoagulation and Iloprost for heparin-induced thrombocytopenia: a case report.

In patients who receive heparin for anticoagulation, there can be a mild, transient thrombocytopenia which is usually devoid of complications. However, 6% of these patients experience serious heparin-induced thrombocytopenia (HIT), which can result in coagulation problems or death. Iloprost, a recently developed drug, given in conjunction with heparin, can be used to manage the patient with HIT. Two cases reported are of patients diagnosed with HIT and their management with Iloprost.

The role of Cayo Santiago in primate field studies.

Cayo Santiago has provided the opportunity to study primate biology in a free-ranging neutral environment free of provocative human influences. Rarely, if ever, does such a situation occur in natural rhesus habitats in Asia. This Cayo Santiago advantage has permitted fine-scale analyses of the details of behavior, ecology, reproduction, genetics, demography, and pathobiology with a greater degree of precision than is possible in the field. At the same time, research on Cayo Santiago has provided valuable baselines for comparative work with natural populations in Asia. Field and laboratory work with the Cayo Santiago colony has produced an impressive number of pioneering studies, from the first investigations of Carpenter in the late 1930's, to the recent demonstrations of Kessler and Rawlins on the demographic role of tetanus in rhesus population ecology and the effectiveness of an inoculation program in eliminating infectious disease. Few, if any, primate colonies have had such a productive interface of naturalistic studies of behavior and ecology with basic biomedical research.

Population survey of macaques in northern Sulawesi.

A field survey of 25 sites in Sulawesi Utara (north Sulawesi) in 1987 and 1988 found macaques in 16 of these sites. The most viable population of Macaca nigra was found in the Tangkoko reserve at an estimated density of 76.2 monkeys/km2, which is less than one-third the abundance reported in the late 1970s by the MacKinnons. The adjacent reserves of Batuangus and Duasudara had only 22 monkeys/km2, yielding a population estimate for these three contiguous reserves of only 3,655 individuals. Maccaca nigrescens were found in the central and western portions of Dumoga-Bone National Park in densities of 15.5 and 16.4 monkeys/km2, significantly below the density of 27/km2 reported by the MacKinnons. The more peripheral areas of Dumoga-Bone had only 8.15 monkeys/km2, yielding a population estimate of M. nigrescens in Dumoga-Bone of less than 34,000. Our total population estimate for M. nigra and M. nigrescens combined is less than 50,000 individuals, which is considerably below that reported in recent litreture. M. hecki were observed in only two locations, Tangale and Panua Reserves, at low densities of 3.3 to 5.2 monkeys/km2, suggesting its range and abundance have declined since the observations of Groves (pp. 84-124 in THE MACAQUES: STUDIES IN ECOLOGY, BEHAVIOR AND EVOLUTION. D. G. Lindburg, ed. New York, Van Nostrand Reinhold, 1980). Several factors have contributed to population decline in these species: habitat shrinkage, increasing human population pressure, and drought conditions. Group sizes were significantly smaller in our study than in previous ones, and we found a shortage of juveniles and infants.

Growth of pika in laboratory confinement.

Captive-born pikas (Ochotoma princeps) from 13 litters were maintained for up to three months in a laboratory setting. Mean litter size was 2.69 +/- 0.75, with litters of three the most frequent, and representing 68% of all litters observed. Mean individual birthweight was 11.7 g with a range of 8.8 to 16.8 g. Weights were taken every other day from birth, which yielded a growth curve equation of y = 12.18 + 1.72x. There was a strong positive linear correlation between bodyweight and time (r = 0.98, P less than 0.001), and a significant difference was noted between sexes, with females the heaviest. Subjects reached adult weight within 3 months. These data represent the first reports of growth in this species, and indicate that pikas are among the fastest growing species within the order Lagomorpha.

Natural regulation of rhesus monkey populations in Kathmandu, Nepal. Rhesus monkey groups near Kathmandu, Nepal, show demographic patterns of intrinsic population stability.

In Kathmandu valley, two populations of rhesus monkeys which are totally protected, have shown relatively stable numbers over a period of several years. Population stability within heterosexual troops appears to have been maintained through lower birth rates and slightly higher infant and adult mortality rates than in comparable rhesus populations in India which have been subject to trapping. Although the behavioral and physiological mechanisms by which these demographic changes occur are not known, behavioral observations on these populations suggest several possibilities. These data represent the first indication of possible mechanisms for population regulation in natural rhesus populations.

Effects of parental environment on the prevalence of convulsive seizures in Onychomys torridus.

Male and female southern grasshopper mice (Onychomys torridus) were reared in 1 of 3 different parental environments: (a) with the natural male and female parents; (b) with the female parent only; or (c) with foster parents of a closely related species, Peromyscus leucopus. All mice were weaned at 25 days of age, then observed individually in an open field arena at 10-day intervals from 30 to 100 days of age. Twenty-seven of 59 subjects (45.8%) that were reared by the natural parents exhibited convulsive seizures during at least 1 of the 8 tests in the open field arena. The prevalence of convulsive seizures increased significantly in subjects that received altered parental care: 27 of 41 subjects (65.9%) reared by the female parent only or by Peromyscus foster parents seized during at least 1 of the 8 tests in the open field. Subjects from the 3 treatment groups did not differ in the mean number of seizures observed during the 8 open field tests. These results demonstrate a significant influence of the preweaning parental environment on the prevalence of convulsive seizures on Onychomys torridus.

Effects of artificial feeding on aggressive behaviour of rhesus mondeys in India.

Artificial feeding of rhesus monkeys (Macaca mulatta), which provides the major food source for most rhesus groups in rural and urban habitats, is common practice in India. Such feeding results in significant increases in aggressive competition within the monkey groups: during feeding periods the frequencies of aggressive threats, chases, and attacks increased two to six times above those of non-feeding periods in each of eight different groups. Fighting behaviour did not increase in most groups studied, but did show a rise in one large urban group in Calcutta. The implications of these results for the management of primate breeding colonies are discussed.

The development of convulsive seizures in the grasshopper mouse (Onychomys torridus).

Open-field tests were administered to 29 male and 50 female southern grasshopper mice (Onychomys torridus) at 10-day intervals from 30-100 days of age. Convulsive seizures were observed to occur in 9 males and 23 females during at least 1 of the open-field tests. No significant differences appeared in the seizure characteristics of male and female subjects. The potential of O. torridus as an animal model of human epilepsy is discussed.

Amino acids and presynaptic inhibition in the rat cuneate nucleus.

1. Presynaptic inhibition was evoked in the rat cuneate nucleus by a peripheral conditioning stimulus. The dicarboxylic amino acid salts glutamate and aspartate and the neutral amino acids glycine and gamma-aminobutyric acid (GABA) were topically applied to a restricted area of the cuneate nucleus and their effects on both resting primary afferent terminal excitability and the increase in excitability of afferent terminals during presynaptic inhibition determined.2. Aspartate had no effect on either resting primary afferent terminal excitability or on the increase in excitability during presynaptic inhibition.3. Glycine reduced both resting primary afferent terminal excitability and presynaptic inhibition.4. Glutamate increased both resting primary afferent terminal excitability and presynaptic inhibition while GABA increased resting primary afferent terminal excitability but reduced the increase in excitability during presynaptic inhibition.5. The convulsant alkaloids picrotoxin (given intravenously) and bicuculline (topically applied) blocked presynaptic inhibition. The blocking action of picrotoxin was overcome by topical application of GABA but not glutamate.6. Simultaneous measurement of pre- and post-synaptic excitability in the cuneate nucleus showed that while glutamate increased excitability at both sites, GABA increased primary afferent terminal excitability but depressed post-synaptic excitability.7. It is concluded that glycine and glutamate exert non-specific actions on primary afferent terminals similar to their effects at post-synaptic sites elsewhere in the C.N.S. while GABA depolarizes primary afferent terminals by a specific action at the same receptor site as the presynaptic inhibitory transmitter. The possibility is discussed that the presynaptic inhibitory transmitter in the cuneate nucleus is GABA or a closely related substance.