Genetic transformation with untranslatable coat protein gene of <Emphasis Type="Italic">sugarcane yellow leaf virus</Emphasis> reduces virus titers in sugarcane

Sugarcane yellow leaf syndrome, characterized by a yellowing of the leaf midrib followed by leaf necrosis and growth suppression, is caused by sugarcane yellow leaf virus (SCYLV). We produced SCYLV-resistant transgenic sugarcane from a susceptible cultivar (H62-4671) and determined the amount of virus present following inoculation. The transgenic plants were produced through biolistic bombardment of cell cultures with an untranslatable coat protein gene. Presence of the transgene in regenerated plants was confirmed using PCR and Southern blot analysis. The transgenic lines were inoculated by viruliferous aphids and the level of SCYLV in the plants was determined. Six out of nine transgenic lines had at least 10³-fold lower virus titer than the non-transformed, susceptible parent line. This resistance level, as measured by virus titer and symptom development, was similar to that of a resistant cultivar (H78-4153). The selected SCYLV-resistant transgenic sugarcane lines will be available for integration of the resistance gene into other commercial cultivars and for quantification of viral effects on yield.     

The Phe105 loop of Alix Bro1 domain plays a key role in HIV-1 release

Alix and cellular paralogs HD-PTP and Brox contain N-terminal Bro1 domains that bind ESCRT-III CHMP4. In contrast to HD-PTP and Brox, expression of the Bro1 domain of Alix alleviates HIV-1 release defects that result from interrupted access to ESCRT. In an attempt to elucidate this functional discrepancy, we solved the crystal structures of the Bro1 domains of HD-PTP and Brox. They revealed typical "boomerang" folds they share with the Bro1 Alix domain. However, they each contain unique structural features that may be relevant to their specific function(s). In particular, phenylalanine residue in position 105 (Phe105) of Alix belongs to a long loop that is unique to its Bro1 domain. Concurrently, mutation of Phe105 and surrounding residues at the tip of the loop compromise the function of Alix in HIV-1 budding without affecting its interactions with Gag or CHMP4. These studies identify a new functional determinant in the Bro1 domain of Alix.     

The Effect of Activity on the Waking Temperature Rhythm in Humans

Nine healthy female subjects were studied when exposed to the natural light-dark cycle, but living for 17 “days” on a 27h day (9h sleep, 18h wake). Since the circadian endogenous oscillator cannot entrain to this imposed period, forced desynchronization between the sleep/activity cycle and the endogenous circadian temperature rhythm took place. This enabled the effects of activity on core temperature to be assessed at different endogenous circadian phases and at different stages of the sleep/activity cycle. Rectal temperature was measured at 6-minute intervals, and the activity of the nondominant wrist was summed at 1-minute intervals. Each waking span was divided into overlapping 3h sections, and each section was submitted to linear regression analysis between the rectal temperatures and the total activity in the previous 30 minutes. From this analysis were obtained the gradient (of the change in rectal temperature produced by a unit change in activity) and the intercept (the rectal temperature predicted when activity was zero). The gradients were subjected to a two-factor analysis of variance (ANOVA) (circadian phase/ time awake). There was no significant effect of time awake, but circadian phase was highly significant statistically. Post hoc tests (Newman-Keuls) indicated that gradients around the temperature peak were significantly less than those around its trough. The intercepts formed a sinusoid that, for the group, showed a mesor (±SE) of 36.97 (±0.12) and amplitude (95% confidence interval) of 0.22°C (0.12°C, 0.32°C). We conclude that this is a further method for removing masking effects from circadian temperature rhythm data in order to assess its endogenous component, a method that can be used when subjects are able to live normally. We suggest also that the decreased effect of activity on temperature when the endogenous circadian rhythm and activity are at their peak will reduce the possibility of hyperthermia.     

Differential pathogenesis of closely related 2018 Nigerian outbreak clade III Lassa virus isolates

Nigeria continues to experience ever increasing annual outbreaks of Lassa fever (LF). The World Health Organization has recently declared Lassa virus (LASV) as a priority pathogen for accelerated research leading to a renewed international effort to develop relevant animal models of disease and effective countermeasures to reduce LF morbidity and mortality in endemic West African countries. A limiting factor in evaluating medical countermeasures against LF is a lack of well characterized animal models outside of those based on infection with LASV strain Josiah originating form Sierra Leone, circa 1976. Here we genetically characterize five recent LASV isolates collected from the 2018 outbreak in Nigeria. Three isolates were further evaluated in vivo and despite being closely related and from the same spatial / geographic region of Nigeria, only one of the three isolates proved lethal in strain 13 guinea pigs and non-human primates (NHP). Additionally, this isolate exhibited atypical pathogenesis characteristics in the NHP model, most notably respiratory failure, not commonly described in hemorrhagic cases of LF. These results suggest that there is considerable phenotypic heterogeneity in LASV infections in Nigeria, which leads to a multitude of pathogenesis characteristics that could account for differences between subclinical and lethal LF infections. Most importantly, the development of disease models using currently circulating LASV strains in West Africa are critical for the evaluation of potential vaccines and medical countermeasures.     

The lesser wanderer butterfly, Danaus petilia (Stoll 1790) stat. rev. (Lepidoptera: Danainae), reinstated as a species

Abstract  The lesser wanderer butterfly, Danaus ( Anosia ) chrysippus petilia (Stoll) (Lepidoptera: Danainae), has been treated as a subspecies for the last 100 years. New mitochondrial DNA sequence data for D. petilia , in conjunction with allozyme, structural, morphometric and pattern characters, constitute a compelling case for its specific rank. The holotype of D. petilia has never been located and, as the type location is uncertain, a neotype is designated. Fresh material was collected and examined for this project. Danaus petilia and D. chrysippus have been separated at Lydekker's Line for an estimated 1.1 million years, and they remain interfertile. However, as an allopatric taxon, diagnosable from D. chrysippus , D. petilia merits specific status under the phylogenetic species concept. The following pairs of D. chrysippus subspecies are considered to be synonyms, the first member of each pair having priority: chrysippus  +  aegyptius (subspecies), klugii  +  infumata (hybrid phenotypes) and orientis  + liboria (subspecies).     

Antibiotic resistance in coagulase-negative staphylococci isolated from Cope''s gray treefrogs (Hyla chrysoscelis)

Microcin J25 (MccJ25) is a cyclic peptide of 21 unmodified amino acid residues produced by a fecal strain of Escherichia coli. It has previously been shown that the antibiotic activity of this peptide is mainly directed to Enterobacteriaceae, including several pathogenic E. coli, Salmonella and Shigella strains. In this paper we show that MccJ25 acts on the cytoplasmic membrane of Salmonella newport cells producing alteration of membrane permeability, and the subsequent gradient dissipation, that initiate the inhibition of process, such as oxygen consumption. These results, taken together with our in vitro observations [Rintoul et al. (2000) Biochim. Biophys. Acta 1509, 65-72], strongly suggest that the disruption of the cytoplasmic membrane gradient is closely related to the bactericidal activity of MccJ25 in S. newport.     

The role of small ground‐foraging mammals in topsoil health and biodiversity: Implications to management and restoration

Summary Many early Australian records indicate that at the time of European settlement there were extensive tracts of highly productive, and species‐rich, grassy communities and chenopod shrublands. Topsoils in many areas were soft and friable. The rapid development of livestock industries led to most changes to the environment being simplistically ascribed to domestic stock grazing, land clearance, introduced pests (such as rabbits) or changed burning practices. It has also commonly been assumed that the hoof action of domestic stock was the principal cause of the compaction and surface sealing of soils in many areas. However, the rapid soil deterioration also coincided with the dramatic decline or complete extinction of many small native ground‐foraging mammals and the consequent cessation of the soil disturbances and interactions that they created. This paper reviews the role of small mammals in disturbing soils, and implications for incorporation of organic matter, aeration, improvement in infiltration and the provision of suitable sites for seed germination and seedling establishment. This can aid topsoil formation and health by providing substrate for microorganisms, improved water balance and mineral cycles and enhanced soil structure. Seeds and mycorrhizal fungi, that are integral to the establishment and growth of many plants, are spread. Such intermittent disturbance may be an important driving force in determining the pathway of succession and lead to greater biodiversity. Further ongoing research on Australia's small mammals is needed, especially in areas where they are able to move freely in a natural environment and are protected from introduced predators.