Silver nitrate promotes shoot development and plant regeneration of chile pepper (Capsicum annuum L.) via organogenesis

Summary Chile pepper (Capsicum annuum L.) plants were regenerated from cotyledon explantsin vitro in four major stages: bud induction, bud enlargement, shoot elongation, and root development. Bud induction medium contained 0.5 mg/L (2.9μM) indole-3-acetic acid and 2 mg/L (8.9 μM) N⁶-benzyladenine. Bud enlargement occurred, and an occasional shoot appeared when medium with 2 mg/L (6μM) gibberellic acid, 2 mg/L (8.9 μM) N⁶-benzyladenine, and 5 mg/L (29.4 μM) silver nitrate was used. Most shoots elongated after placement on a third medium without plant growth regulators or on fresh plates of bud enlargement medium. Incubations were for 2, 2, and 4 weeks, respectively, at 28.5°C and continuous light. Treatment with silver nitrate was necessary for multiple shoot production and elongation to occur in the third culture stage and was most effective when present in the second-stage medium but not in the bud induction medium. Sixteen to 26% of the shoots rooted in medium with 1 mg/L (5.4 μM) 1-naphthaleneacetic acid after 1 month. Additional shoots transferred to a second rooting medium with 0.1 or 1.0 mg/L (0.54 or 5.4 μM) 1-naphthaleneacetic acid developed roots, increasing the overall rooting efficiency to 70–72%. Most rooted shoots grew well and produced viable seeds when grown in the greenhouse. Other cytokinins tested for plant regeneration were zeatin and thidiazuron. Zeatin induced few shoots and fewer well-developed plants. Thidiazuron induced multiple shoots 4 months after culture began, but many were small and did not elongate further. Phytagar tissue culture grade proved superior to other agars tested, increasing bud induction frequency from 0-33% to 80–93% and eliminating explant hyperhydricity.     

Amino-terminal maturation of the Bordetella pertussis filamentous haemagglutinin

The 220 kDa filamentous haemagglutinin (FHA) is a major adhesin of Bordetella pertussis and is produced from a large precursor designated FhaB. Although partly surface associated, it is also very efficiently secreted into the extracellular milieu. Its secretion depends on the outer membrane accessory protein FhaC. An 80 kDa N-terminal derivative of FHA, named Fha44, can also be very efficiently secreted in a FhaC-dependent manner, indicating that all necessary secre tion signals are localized in the N-terminal region of FhaB. A comparison of predicted and apparent sizes of FHA derivatives, in addition to immunoblot analyses of cell-associated and secreted FHA polypeptides, indicated that FhaB undergoes N-terminal maturation by the cleavage of an 8–9 kDa segment. However, phenotypic analyses of translational lacZ and phoA fusions showed that this segment does not function as a typical signal peptide. Co-expression of the Fha44-encoding gene with fhaC also did not allow for secretion of Fha44 in Escherichia coli. High levels of secretion could, however, be observed when the OmpA signal peptide was fused to the N-terminal end of Fha44. Regardless of the OmpA signal peptide-Fha44 fusion point, the E. coli-secreted Fha44 had the same M_r as that secreted by B. pertussis, indicating that the N-terminal proteolytic maturation does not require a B. perfussis-specific factor. Similar to FHA, the B. pertussis-secreted Fha44 contains an as yet uncharacterized modification at its N-terminus. This modification did not occur in E. coli and is therefore not required for secretion. The N-terminus of Fha44 secreted by E. coli was determined and found to correspond to the 72nd residue after the first in-frame methionine of FhaB. The N-terminal modification was also found not to be required for haemagglutination or interaction with sulphated glycoconjugates.     

Identification of new early auxin markers in tobacco by mRNA differential display

Differential display of mRNA has been improved by developing a two-step PCR amplification procedure. The modified differential display has been applied to identify early alterations of mRNA expression in response to auxin treatment of tobacco seedlings. This approach has led to the isolation of four fragments corresponding to auxin-up-regulated mRNAs. One, named GO15-13, shows significant homology with the 3 end of the coding region of the soybean SAUR X10A [10]. The three other fragments present no homology with sequences available in the databases and constitute potential new early auxin markers.     

Evidence against plant “apparency” as a constraint on evolution of insect search efficiency (Lepidoptera: Nymphalidae)

Two conspecific butterfly populations (Euphydryas editha, Edith's checkerspot) have each undergone evolutionary diet expansion. Within each population, butterflies oviposited on two morphologically distinct host species. Using a traditional definition of apparency, insects searched efficiently for an unapparent host that was longstanding but inefficiently for an unapparent host that was novel. This is interpreted as indicating that search efficiency evolves after colonization of a novel host regardless of the plant's visual apparency. Discussion of the result indicates that apparency should be defined nonanthropomorphically in the context of a specified insect's perceptual abilities.     

Syndromic surveillance for influenzalike illness

Emergency department data are currently being used by several syndromic surveillance systems to identify outbreaks of natural or man-made illnesses, and preliminary results suggest that regular outbreaks might be detected earlier with such data than with traditional reporting. This article summarizes a retrospective study of 5 influenza seasons in Ottawa,Canada; time-series analysis was used to look for an association between consultation to the emergency department for influenzalike illness and the isolation of influenza virus in the community. The population studied included both children and adults consulting to 3 local hospitals. In 4 seasons, visits to the emergency department involving children younger than 5 years consulting mainly for fever and for respiratory symptoms peaked 1 to 4 weeks before the isolation of influenza virus in the community. If monitored regularly for the presence of key symptoms, pediatric hospitals might be efficient and cost-effective sentinels of influenza and of other infectious diseases.     

Differential fitness effects of immunocompetence and neighbourhood density in alternative female lizard morphs

1. A growing number of studies demonstrate that natural selection acts on traits important in whole animal performance and physiology. 2. Here we describe a heritable polymorphism in female dorsal pattern in the lizard Anolis sagrei (Dumeril & Bibron 1837). 3. Morphs did not differ in body size or habitat use (perch diameter), however, we show that the social environment, estimated by the number of female neighbours, had different selective effects on alternative morphs in nature. 4. We show that morphs displayed a significantly different immune response to phytohaemagglutinin. Furthermore, natural selection differentially acted on combinations of female morph and immunocompetence, favouring high levels of immune function in one morph and low levels of immune function in the other. 5. We discuss the possibility that morph-specific investments in life-history traits may lead to correlational selection between traits, even when those traits are likely to be determined by different genetic loci.