The Control of Vascular Branching in Coleus 2. The Corner Traces

Corner trace connections are less well defined than those ofthe side bundle in Coleus, the locations of branch points, branchpartners, and number of connections made by a corner trace beingmore variable. The auxin balance between corner traces was alteredby leaf removal and by application of exogenous auxin. Branchingof new strands was shifted toward the pre-existing strand withthe lower auxin flux, but only within a narrow range of developmentalstages and with the imposition of a large auxin imbalance. Branchingoccurred only in nodal regions, as in control plants. Thus,auxin balance can be made to control xylem strand branching,but it does not account fully for the control of vascular branchingin intact plants. In the intact pattern, corner trace branchesappear to be directed toward the pre-existing strand with thehigher auxin flux. It is proposed that, in the vicinity of astrand with high flux, auxin is transported laterally withinthe nodal vascular cambium, facilitating vessel differentiationbetween strands in the derivatives of the vascular cambium.These vessels comprise the connections between traces. Coleus, vascular differentiation, vascular anatomy, vascular branching, vascular patterns, auxin, auxin balance, node     

Probability of Detecting Band-Tailed Pigeons During Call-Broadcast Versus Auditory Surveys

Abstract: Estimates of population trend for the interior subspecies of band-tailed pigeon (Patagioenas fasciata fasciata) are not available because no standardized survey method exists for monitoring the interior subspecies. We evaluated 2 potential band-tailed pigeon survey methods (auditory and call-broadcast surveys) from 2002 to 2004 in 5 mountain ranges in southern Arizona, USA, and in mixed-conifer forest throughout the state. Both auditory and call-broadcast surveys produced low numbers of cooing pigeons detected per survey route (x̄ ≤ 0.67) and had relatively high temporal variance in average number of cooing pigeons detected during replicate surveys (CV ≥ 161%). However, compared to auditory surveys, use of call-broadcast increased 1) the percentage of replicate surveys on which ≥1 cooing pigeon was detected by an average of 16%, and 2) the number of cooing pigeons detected per survey route by an average of 29%, with this difference being greatest during the first 45 minutes of the morning survey period. Moreover, probability of detecting a cooing pigeon was 27% greater during call-broadcast (0.80) versus auditory (0.63) surveys. We found that cooing pigeons were most common in mixed-conifer forest in southern Arizona and density of male pigeons in mixed-conifer forest throughout the state averaged 0.004 (SE = 0.001) pigeons/ha. Our results are the first to show that call-broadcast increases the probability of detecting band-tailed pigeons (or any species of Columbidae) during surveys. Call-broadcast surveys may provide a useful method for monitoring populations of the interior subspecies of band-tailed pigeon in areas where other survey methods are inappropriate.     

SITE TO SITE VARIATION IN THE SOAP CHAMBER TEST

This investigation was conducted to examine the contribution of intrasite variation on the volar forearm to the overall variation in irritation under the conditions of a soap chamber test. Six sites on each forearm of human volunteers were patched with an eight percent aqueous solution of a commercial bar soap, known to be moderately irritating. Clinical evaluations of the sites were made independently by two judges twenty-four hours after the first patch application and six hours following applications conducted over the next four consecutive days. Site to site variability was estimated to be only 3.2% of the total variance component. It is suggested that as with any biologic assay, this variance can be reduced by an increase in the number of panelists.     

The energetic cost of calling in the variable field cricket, Gryllus lineaticeps

Abstract. Female preferences for conspicuous male calls have been documented in many groups. However, relatively few studies have examined the metabolic costs associated with the production of call types preferred by females. We measured the oxygen consumption of calling male Gryllus lineaticeps Stål crickets using closed chamber respirometry. Calling song was recorded concurrently. The average increase in mass-specific oxygen consumption during calling was 2.7 times basal rates of oxygen consumption, and calling males consumed approximately 1.2ml O₂g^-lh^-1. Oxygen consumption increased with increasing chirp rate and pulse duration, but not with increasing chirp duration. Females of this species prefer higher chirp rates, thus some call types that increase the male's attractiveness to females require more metabolic energy to produce.     

Chlorophyll Destruction in Lemon Fruit by Light and 2',4'Dichloro 1-Cyanoethane-sulphonanilide

Chlorophyll content decreased when excised lemon fruits were exposed to light. A quantitative model for the photodestruction of chlorophyll exhibited reasonable agreement with data on in vivo destruction of chlorophyll. Photodestruction of chlorophyll was enhanced by treating fruit with 2′,4′-dichloro-l-cyanoethane-sulphonanilide (R33417). Measurable enhancement of chlorophyll destruction was observed with concentrations of R33417 as low as 10 μg/l. Maximum activity was achieved at approximately 600 μg/1. R33417 treatment enhanced photodestruction of chlorophyll to a greater extent at higher photon flux densities.