CHROMOSOME NUMBERS OF CAMPANULACEAE. II. THE LOBELIA TUPA COMPLEX OF CHILE

Gametic chromosome numbers are reported for 27 collections representing the four species of the Lobelia tupa complex (Campanulaceae, Lobelioideae) in Chile; all are n = 21. This represents the first report of chromosome numbers for L. bridgesii Hook. & Arn., L. excelsa Bonpl., and L. polyphylla Hook. & Arn., and confirms previous reports of this number in L. tupa L. As the basic chromosome number of Lobelioideae is x = 7, these species are interpreted as hexaploids. Higher polyploids are extremely rare among Lobelioideae; most of those previously reported have been either sporadic individuals or populations within an otherwise diploid or tetraploid species, or occasional species within an otherwise diploid and tetraploid lineage. This is the first report of an entire complex of lobelioid species that is uniformly hexaploid. This suggests that the Chilean endemics are relatively derived within Lobelia, and offers some support for the monophyly of the complex.     

Species-specific algal responses to zooplankton: experimental and field observations in three nutrient-limited lakes

A series of 4-day manipulations of zooplankton biomass and nutrientavailability was performed in enclosures in three lakes to determinespecies-specific algal responses to herbivory and nutrient enrichment.Algal performance in enclosures was compared to the relationshipsbetween weekly algal growth rates and the zooplankton in situ.When in situ growth rates were significant functions of zooplanktonbiomass, the responses were generally consistent with responsesin the enclosure experiments. The importance of both nutrientsand zooplankton in mediating algal growth was demonstrated bynumerous observations: strong algal community response to enrichment,unimodal or positive responses of certain algal taxa to zooplanktonbiomass, differences in degree of nutrient limitation amongthe algal response types, lack of nutrient limitation of non-grazedalgal taxa and a preponderance of taxa with no net responseto increasing zooplankton biomass. Variation in the zooplanktoncommunity may be the largest source of variability in nutrientsupply rate during summer in stratified lakes, and causes substationalvariability in the algae. Algae responded more strongly to changesin zooplankton composition than to changes in zooplankton biomass.We conclude that, due to the close coupling of phytoplanktonand zooplankton communities in these nutrient-limited lakes,major compositional changes in the zooplankton have greatereffects on the algae than do changes in biomass of grazers alreadypresent. ¹Present address: Division of Environmental Studies, Universityof California, Davis, CA 95616, USA ²Present address: Division of Biological Sciences, Universityof California, Davis, CA 95616, USA     

Effect of a selectiveβ 2-adrenergic agonist (Cenbuterol) on energy balance and body composition in normal and protein deficient rats

In rats fed a normal (22% protein) diet, injection of clenbuterol (1 mg/kg/d for 21 d) did not affect energy intake, energy expenditure or weight gain, but reduced energetic efficiency, and fat and energy gains and increased body protein content. Presenting a low-protein (8%) diet reduced energy intake, gain and efficiency, body protein content and the mass of the gastrocnemius muscle when compared to rats fed the control diet. Injection of the protein-deficient rats with clenbuterol (1 mg/kg/d for 21 d) caused hypophagia and reduced body weight and energy gains, energy expenditure and total body fat. However, the total body content of protein was not significantly reduced and the percentage of body protein in this protein deficient, clenbuterol-treated group was greater than that of untreated rats on both the high- and low-protein diets. The ratio of body protein to fat following clenbuterol treatment was increased by over 50% in both normal and protein-deficient rats. The results show that in protein deficient animals, clenbuterol treatment may help conserve body protein at the expense of fat, resulting in a smaller, but leaner body mass.     

Intrasexual Competition and Mate Choice in Rocky Mountain Bighorn Sheep

Rocky Mountain bighorn (Ovis canadensis canadensis) rams employed three distinct mating tactics. When tending, rams defended single estrous ewes. In coursing, rams forced copulations with defended ewes, and, in blocking, rams sequestered ewes from more dominant rams. Ewes utilized a traditional area when tended, attempted to escape to this area when blocked, and resisted coursing ram attempts to force copulations. Between-year variation in the dispersion of estrous ewes about the tending area strongly influenced the consort and probably mating success of dominant rams. Thus, ewe spatial predictability during estrus — achieved by clustering in tended estrus and resisting blocking rams — appears to be an important mechanism of mate choice in this species. Ewes apparently did not gain material or risk-related benefits by mating dominant rams. That such males provide ewes with “good genes” is an attractive remaining possibility.     

Ethylene production by loblolly pine seedlings associated with water stress

Effects of water stress on production of ethylene and its precursor, 1-aminocyclopropane-1-carboxylic acid (ACC), by loblolly pine ( Pinus taeda L.) seedlings from a Texas drought-hardy and a Virginia Coastal Plain source were investigated. Ethylene production rates in needles from the Virgnia source increased slightly with initial stress (-1.3 MPa), declined until water potential reached -1.6 MPa and then increased sharply at -2.5 MPa. The ethylene production rates in needles from the Texas also increased slightly with initial stress, then decreased with decreasing water potential. Ethylene production by root tissue was two to three times higher than needle tissue and decreased with decreasing water potential. ACC concentrations in needles of both seed sources decreased as water potential began decreasing. Below -1.4 MPa, ACC levels started increasing (Texas source) or remained constant until -2.8 MPa (Virginia source) at which time its level increased three-fold. Mean ACC levels in root tissue [122 nmol (g dry weight)⁻¹] were slightly higher than the mean levels in the needle tissue [92 nmol (g dry weight) ⁻¹]; roots apparently were more efficient in converting it to ethylene since ethylene production was two to three times higher than needle tissue. The modulation of ethylene synthesis by ACC synthase and ethyleneforming enzyme appeared to be influenced by stress level, organ and seed source.     

‘Mental’ in ‘southie’: Individual,family, and community responses to psychosis in South Boston

The deinstitutionalization of psychiatric patients is a deeply cultural as well as political task. It entails the sharing of responsibility for human distress with family and community. Consequently, the locus of social control has also shifted from psychiatric and medical expertise to community and legal institutions. Diagnosis and treatment models must be more compatible with lay explanatory models. This paper explores the various meanings of going mental and being mental in the white, working class, ethnic neighborhood of South Boston. The data are extracted from a study of the impact of deinstitutionalization on a cohort of middle-aged, psychiatric patients discharged from Boston State Hospital in the attempt to return them to community living. Individual, family, and community responses to, and interpretations of, the symptoms of mental distress are discussed. The study indicates that even seriously disturbed individuals are sensitive to cultural meanings and social cues regarding the perception, expression, and content of psychiatric episodes. While madness invariably disenfranchises, it does not necessarily deculturate the individual.     

Biochemical characterization of individual normal, floppy and rheumatic human mitral valves.

Human mitral valves (32 floppy and 17 rheumatic) obtained at surgery were analysed and compared with 35 normal (autopsy) valves. Total amounts of collagen, proteoglycan and elastin were increased approx. 3-fold in floppy and rheumatic valves. The water content of rheumatic cusps was lower than normal. The most significant changes in floppy valves were the 59% increase in mean value of the proteoglycan content, a large increase in the ease of extractability of proteoglycans from 26.7 to 57.2% of the total and a 62% increase in mean value of the elastin content in the anterior cusps. Normal human mitral valve cusps contained a mean proportion of 29.3 (and chordae 26.6) type III collagen (as % of total types III + I collagen), the values increasing significantly to 33.2 and 36.3% respectively in chronic rheumatic disease. The ratio observed in floppy valves depended on the extent of secondary surface fibrosis, which could be demonstrated histologically; in valve cusps with considerable secondary fibrosis, the percentage of type III increased significantly (to 34.4%), whereas it decreased significantly (to 25.2%) when fibrosis was negligible. It is concluded that the ratio of collagen types in floppy valves reflects the extent of secondary fibrosis rather than the pathogenesis of the disrupted collagen in the central core of the valve.