Does fire drive fatty acid composition in seed coats of physically dormant species?

Seed dormancy is the key driver regulating seed germination, hence is fundamental to the seedling recruitment life-history stage and population persistence. However, despite the importance of physical dormancy (PY) in timing post-fire germination, the mechanism driving dormancy-break within seed coats remains surprisingly unclear. We suggest that seed coat chemistry may play an important role in controlling dormancy in species with PY. In particular, seed coat fatty acids (FAs) are hydrophobic, and have melting points within the range of seed dormancy-breaking temperatures. Furthermore, melting points of saturated FAs increase with increasing carbon chain length. We investigated whether fire could influence seed coat FA profiles and discuss their potential influence on dormancy mechanisms. Seed coat FAs of 25 species within the Faboideae, from fire-prone and fire-free ecosystems, were identified and quantified through GC-MS. Fatty acid profiles were interpreted in the context of species habitat and interspecific variation. Fatty acid compositions were distinct between species from fire-prone and fire-free habitats. Fire-prone species tended to have longer saturated FA chains, a lower ratio of saturated to unsaturated FA, and a slightly higher relative amount of FAs compared to fire-free species. The specific FA composition of seed coats of fire-prone species indicated a potential role of FAs in dormancy mechanisms. Overall, the distinct FA composition between fire-prone and fire-free species suggests that chemistry of the seed coat may be under selection pressure in fire-prone ecosystems.

Personality disorder, symptoms and dexamethasone suppression in depression.

The presence of Personality Disorder (PD) in depressed patients admitted to the acute wards of a psychiatric hospital was assessed using Tyrer's Personality Assessment Schedule, and its relationship to depressive symptoms, improvement after 2 weeks, and the dexamethasone suppression test was examined. 75.4% of the sample met Tyrer's criteria for a PD diagnosis. The initial symptoms of patients with personality disorder did not differ from those without PD. However patients with PD improved more slowly, and had significantly higher symptom scores after 2 weeks. Patients with PD also showed previous history of more depressive episodes, a younger first age of onset, and more frequent and severe previous suicide attempts, in addition to history of unstable marriage. No difference in dexamethasone suppression was found. These findings suggest that presence of personality disorder is related primarily to course of illness and life history, rather than symptom pattern.

Secondary amines isolated from venom gland of dolichoderine antTechnomyrmex albipes.

A series of unsaturated secondary amines have been isolated from the dolichoderine antTechnomyrmex albipes (F. Smith). The major components of the mixture have been shown by spectroscopic procedures to be dinon-8-enylamine, andN-hept-6-enylnon-8-enamine, and these structural assignments have been confirmed by synthesis. Mass spectrometry indicates the presence of trace amounts of the bis C11 amine and the C9-C11 amine. The four amines, present in total at approximately 2.8µg/ant, are located in the gaster of the insect in a gland that is considered to be the venom gland although it is atypical from a morphological standpoint.

The Leaf Oil of Liquidambar styraciflua.

The leaf oil of LIQUIDAMBAR STYRACIFLUA was obtained by simultaneous distillation extraction and analysed by GC and GC-MS. Thirty-six components, all ter-penoid, were identified, with the major constituents being terpinen-4-ol, alpha-pinene and sabinene. The high terpinen-4-ol and low 1,8-cineole content make the oil of some pharmacological interest.

Identification by methane chemical ionization gas chromatography/mass spectrometry of the products obtained by steam distillation and aqueous acid extraction of commercial Piper methysticum.

Bornyl cinnamate has been identified as a constituent of kava resin and of the steam distillate of Piper methysticum. 5-Hydroxydihydrokawain was identified in commercial samples of P. methysticum originating from Vanuatu provided an initial aqueous extraction was employed. Commercial preparations, and fresh samples of the root of this plant from Fiji, lacked this compound. Two previously described N-cinnamoyl pyrrolidine alkaloids were also observed along with stigmasterol in kava resin from Fiji and Vanuatu. The products derived from aqueous 2 M hydrochloric acid extraction of P. methysticum were determined from methane chemical ionization gas chromatography/mass spectrometry analysis which identified a series of hydroxylated compounds (15a-d) derived from formal decarbonylation of the parent kava lactones. The products (13a-c) of dehydration of these compounds were also observed. The efficiency of kava resin extraction from plant material by water (the traditional method of preparation of the kava beverage) was typically 5-10% of that recovered by direct extraction with an organic solvent.

Novel pyrazines from the head of Australian ponerine antRhytidoponera metallica.

The novel pyrazines, (E)- and (Z)-5-methyl-3-(2-methylbutyl)-2-(3-methylbut-1-enyl)pyrazine, (E)- and (Z)-5-methyl-3-isopentyl-2-(3-methylbut-1-enyl) pyrazine, (E)- and (Z)-5-methyl-3-(2-methylbutyl)-2-(3-methylpent-1-enyl)pyrazine, (E)- and (Z)-5-methyl-3-isopentyl-2-(3-methylpentl-enyl) pyrazine, together with the known pyrazines, 2,5-dimethyl-3-(2-methylbutyl)pyrazine and 2,5-dimethyl-3-isopentylpyrazine, have been identified from the head of the Australian ponerine antRhytidoponera metallica. Alkanes and alkenes, in small amounts, were also detected.

Patients with myotonic dystrophy, a possible segmental progeroid syndrome, and Duchenne muscular dystrophy have fibroblasts with normal limits for in vitro lifespan and growth characteristics.

Myotonic dystrophy (MyD) has been suggested to be a segmental progeroid syndrome in man, as this syndrome has some clinical manifestations of premature aging. Fibroblasts from patients with other progeroid syndromes have been shown to have diminished in vitro lifespans or growth characteristics; therefore, it was of interest to study cellular senescence in fibroblasts from patients with MyD. Fibroblast cultures from patients with Duchenne muscular dystrophy (DMD) were used as additional controls, as premature aging is not associated with this genetic disorder. Primary skin fibroblast cultures obtained from patients with MyD or DMD and from age-sex matched controls were grown in DMEM plus 10% FBS. The in vitro lifespan was determined by either a 1:4 split ratio or with a constant initial inoculum of 1 times 10(4) cells/cm2, followed by determination of the final density at weekly intervals. Our results demonstrate that there is no difference in the limits of the in vitro lifespan for either the MyD or DMD fibroblast strains compared to the controls. Likewise, no difference could be detected in the growth characteristics of these cells. The only observable difference was that the pooled age-matched controls and MyD cultures had a shorter in vitro lifespan than the DMD group and their pooled controls, a finding expected because of the age of the patients in each group. Unlike the other progeroid syndromes, MyD fibroblasts have normal limits for in vitro lifespan. MyD is probably not closely related to the other premature aging syndromes, although there is an increasing phenotypic expression as a function of age.