WATER RELATIONS OF TWO CALIFORNIA CHAPARRAL SHRUBS

Water use patterns of two California chaparral shrub species, chamise (Adenostoma fasciculatum H. and A.) and Stanford manzanita (Arctostaphylos stanfordiana Parry), were compared during summer drought. Observations of diurnal and seasonal courses of shoot water potential, leaf conductance and transpiration revealed that chamise was more conservative in water use than manzanita. Evidence obtained cast doubt on a hypothesis previously proposed to explain an anomalous pattern of shoot water potential in chamise.     

THE DISTRIBUTION OF COCCIDIOIDOMYCOSIS IN SOUTHERN CALIFORNIA

In coccidioidin skin test surveys among persons of high school age in Saugus, Canoga Park, Banning and Palm Springs areas the average incidence of positive reaction was 15 per cent. Although considerably less than the 68 per cent incidence reported among high school students of Kern County, it is high enough to indicate pockets of relatively high endemicity in Southern California below the San Joaquin Valley.Histoplasmin tests were performed on most of the persons tested with coccidioidin in this survey. The over-all incidence of positive reaction in the group was 7.6 per cent. Most of the subjects with positive reaction to histoplasmin gave a history of having previously lived in some area in the central United States where histoplasmosis is known to be endemic.A few subjects who had positive reaction to coccidioidin tests and who had lived in areas known to be endemic for coccidioidomycosis but not for histoplasmosis, also had positive reaction to histoplasmin. However, the induration produced was always smaller than that caused by the coccidioidin reaction, and there was minimal confusion in interpreting the tests.     

CHARRED WOOD STIMULATED GERMINATION OF TWO FIRE-FOLLOWING HERBS OF THE CALIFORNIA CHAPARRAL AND THE ROLE OF HEMICELLULOSE

Germination of the fire-following chaparral herbs, Emmenanthe penduliflora (Hydrophyllaceae) and Eriophyllum confertiflorum (Asteraceae), previously has been shown to be stimulated by charred wood from the widespread chaparral shrub Adenostoma fasciculatum (Rosaceae). A series of investigations undertaken to clarify this effect gave the following results. Light is not required, but may enhance the response. The effect is not limited to A. fasciculatum but is produced by a wide variety of chaparral and non-chaparral woods. Charring is not necessary; wood heated to 175 C for 30 min produced the same germination stimulation. The stimulatory compound is water soluble, effective within 24 hr exposure and active at 0.04 g/50 cc soil. Germination was stimulated by heated xylan, a hemicellulose, and by heated glucuronic acid, a common side chain of xylan and other hemicelluloses. Heating produced changes in the color and consistency of xylan and glucuronic acid. An oligosaccharin-type molecule is postulated to be produced by heating xylan or other hemicelluloses with glucuronic acid side chains. Previously described oligosaccharins are derived from galactouronic acid and xyloglucan which are structurally and functionally related to compounds tested here.     

INTRASPECIFIC GENETIC DIFFERENTIATION IN CALIFORNIA SEA LIONS (ZALOPHUS CALIFORNIANUS) FROM SOUTHERN CALIFORNIA AND THE GULF OF CALIFORNIA

Intraspecific patterns of mitochondrial DNA sequence variation were determined among California sea lions ( Zalophus califomianus californianus ) from three colonies along the Pacific coast of southern and Baja California and one colony in the Gulf of California. We found no variation in 368 base pairs (bp) of cytochrome b sequence among 40 sea lions from these localities, but analysis of 360 base pairs of control region revealed eleven genotypes. The four genotypes found in the Gulf of California population were unique and phylogenetically distinct from those found in sea lions along the Pacific coast. The average sequence divergence between Gulf and Southern California genotypes was 4.3%, suggesting a relatively long period of isolation. However, colonies along the Pacific coast, which are less than 200 km apart, shared mtDNA genotypes, indicating that recent genetic exchange has occurred between them. Therefore, we suggest that regional female philopatry exists in California sea lions. Regional boundaries may be related to oceanic currents or patchiness in the distribution of resources. Further research is needed to better understand the underlying causes of genetic differentiation in the California sea lion.     

SNAKE VENOM POISONING IN SOUTHERN CALIFORNIA

The annual incidence of rattlesnake bite in Southern California is approximately 1 per 75,000 population. The case fatality rate is 1.5 per cent. The snakes implicated in the greatest number of injuries are the southern Pacific rattlesnake, the red diamond rattlesnake and the sidewinder.Rattlesnake venom produces deleterious changes in the blood cells, defects in blood coagulation, injury to the intimal linings of vessels, damage to the heart muscle, alterations in the respiratory cycle and, to a lesser extent, changes in neuromuscular conduction.The most frequently observed symptoms and signs following ophidiasis in this area are swelling and edema, pain, ecchymosis, swelling of the regional lymph nodes, weakness, sweating, increased body temperature, faintness, and hemorrhagic vesiculations. First aid treatment consists of immobilization of the affected part, application of a constriction band, incision and suction with subsequent local application of ice packs. Treatment in hospital consists of administration of antivenin, antitetanus agent and antibiotic. Transfusions, oxygen and a corticosteroid may be indicated in some cases.