Germination and growth responses of hybridizing Carpobrotus species (Aizoaceae) from coastal California to soil salinity

Germination, growth, and physiological responses of hybridizing Carpobrotus from coastal California to soil salinity were studied. Hybrids are presumably the result of hybridization and introgression between the exotic Carpobrotus edulis, a succulent perennial invading coastal habitats, and the native or long-naturalized C. chilensis. Germination responses were investigated at 0, 10, 20, and 50% seawater. Seedling growth and physiology were compared by irrigating seedlings with solutions of the same seawater concentrations and in low and high nutrients. Germination was inhibited in the presence of salt, but recovered after transferring the seeds to fresh water. Seeds exposed to salt had higher final germination rates than control. Growth of Carpobrotus was slightly enhanced by low seawater concentrations but reduced at high salinity at both nutrient regimes. Leaf cell sap osmolarity increased with increasing soil salinity, and taxa did not differ significantly in this physiological adjustment. Leaf carbon isotope ratios (∂¹³C) ranged from −28 to −22‰ and became less negative at higher salinities, indicating an improved water use efficiency in the seedlings at high salt concentrations. In addition, ∂¹³C values were generally less negative at high than at low nutrients. Differences among taxa were generally small. The results show that salinity affects both establishment and growth of hybridizing Carpobrotus. The overall weak species differences in salt tolerance indicate that the exotic C. edulis can occupy the same sites as C. chilensis in terms of salinity. The similarity of hybrids in their response to salinity suggests that they may contribute to the invasion by Carpobrotus.     

Evolutionary biology and the treatment of signs and symptoms of infectious disease

When viewed from an evolutionary perspective, manifestations of infectious diseases can be classified as (1) adaptations of the host to counteract harmful aspects of the disease, (2) adaptations of the pathogen to manipulate the host, or (3) “side effects” of the disease that do not serve adaptive functions for either the host or the pathogen. Although the functions of most manifestations are not known, support or rejection of these hypotheses should be readily derivable in many cases from analyses of existing data and relatively simple experiments. This approach should lead to improved medical treatment because preferred treatment depends on assessment of the validity of the three explanations. As an illustration, this perspective and its consequences for therapy are analyzed for fever, rhinorrhea and diarrhea.     

Intracellular recording from a spider vibration receptor

The present study introduces a new preparation of a spider vibration receptor that allows intracellular recording of responses to natural mechanical or electrical stimulation of the associated mechanoreceptor cells. The spider vibration receptor is a lyriform slit sense organ made up of 21 cuticular slits located on the distal end of the metatarsus of each walking leg. The organ is stimulated when the tarsus receives substrate vibrations, which it transmits to the organ’s cuticular structures, reducing the displacement to about one tenth due to geometrical reasons. Current clamp recording was used to record action potentials generated by electrical or mechanical stimuli. Square pulse stimulation identified two groups of sensory cells, the first being single-spike cells which generated only one or two action potentials and the second being multi-spike cells which produced bursts of action potentials. When the more natural mechanical sinusoidal stimulation was applied, differences in adaptation rate between the two cell types remained. In agreement with prior extracellular recordings, both cell types showed a decrease in the threshold tarsus deflection with increasing stimulus frequency. Off-responses to mechanical stimuli have also been seen in the metatarsal organ for the first time.     

Methods to quantify soft-tissue based facial growth and treatment outcomes in children: a systematic review

Context

Technological advancements have led craniofacial researchers and clinicians into the era of three-dimensional digital imaging for quantitative evaluation of craniofacial growth and treatment outcomes.

Objective

To give an overview of soft-tissue based methods for quantitative longitudinal assessment of facial dimensions in children until six years of age and to assess the reliability of these methods in studies with good methodological quality.

Data Source

PubMed, EMBASE, Cochrane Library, Web of Science, Scopus and CINAHL were searched. A hand search was performed to check for additional relevant studies.

Study Selection

Primary publications on facial growth and treatment outcomes in children younger than six years of age were included.

Data Extraction

Independent data extraction by two observers. A quality assessment instrument was used to determine the methodological quality. Methods, used in studies with good methodological quality, were assessed for reliability expressed as the magnitude of the measurement error and the correlation coefficient between repeated measurements.

Results

In total, 47 studies were included describing 4 methods: 2D x-ray cephalometry; 2D photography; anthropometry; 3D imaging techniques (surface laser scanning, stereophotogrammetry and cone beam computed tomography). In general the measurement error was below 1 mm and 1° and correlation coefficients range from 0.65 to 1.0.

Conclusion

Various methods have shown to be reliable. However, at present stereophotogrammetry seems to be the best 3D method for quantitative longitudinal assessment of facial dimensions in children until six years of age due to its millisecond fast image capture, archival capabilities, high resolution and no exposure to ionizing radiation.     

<Emphasis Type="Italic">Paenibacillus</Emphasis>—a predominant endophytic bacterium colonising tissue cultures of woody plants

High densities of endophytic bacteria were found in plant material from poplar, larch and spruce that had been micropropagated for at least 5 years. The majority of these bacteria were assigned to the genus Paenibacillus based on the sequencing of the 16S rRNA genes. Other endophytic bacteria such as Methylobacterium, Stenotrophomonas or Bacillus could also be found but only in some tissue cultures. Certain species or strains of Paenibacillus, especially those with a close relationship to P. humicus, seemed to accumulate under in vitro conditions without visible negative influences on the plant’s development. Poplar microcuttings inoculated with the endophytic Paenibacillus isolate 22 showed significantly more roots per cutting and higher root length in comparison to the control plants after 3 weeks.