Trophic ecology of parabiotic ants: Do the partners have similar food niches?

Organisms associated with another species may experience both costs and benefits from their partner. One of these costs is competition, which is the more likely if the two species are ecologically similar. Parabioses are associations between two ant species that share a nest and often attend the same food sources. Albeit parabioses are probably mutualistic, parabiotic partners may compete for food. We therefore investigated feeding niches and dietary overlap of two parabiotically associated ants in Borneo using cafeteria experiments and stable isotope analyses. The two species strongly differed in their food choices. While Crematogaster modiglianii mostly foraged at carbohydrate‐rich baits, Camponotus rufifemur preferred urea‐rich sources. Both species also consumed animal protein. The ¹⁵N concentration in Ca. rufifemur workers was consistently lower than in Cr. modiglianii. Camponotus rufifemur but not Cr. modiglianii possesses microbial endosymbionts, which can metabolize urea and synthesize essential amino acids. Its lower ¹⁵N signature may result from a relatively higher intake of plant‐based or otherwise ¹⁵N‐depleted nitrogen. Isotopic signatures of the two partners in the same parabiosis showed strongly parallel variation across nests. As we did not find evidence for spatial autocorrelation, this correlation suggests an overlap of food sources between the two ant species. Based on model simulations, we estimated a diet overlap of 22–66% for nitrogen sources and 45–74% for carbon sources. The overlap may arise from either joint exploitation of the same food sources or trophallactic exchange of food. This suggests an intense trophic interaction and potential for competition between the parabiotic partners.     

A study of the relationships of interactions between Asp-201, Na+ or K+, and galactosyl C6 hydroxyl and their effects on binding and reactivity of beta-galactosidase.

The interactions between Na+ (and K+) and Asp-201 of beta-galactosidase were studied. Analysis of the changes in Km and Vmax showed that the Kd for Na+ of wild type beta-galactosidase (0.36 +/- 0.09 mM) was about 10x lower than for K+ (3.9 +/- 0.6 mM). The difference is probably because of the size and other physical properties of the ions and the binding pocket. Decreases of Km as functions of Na+ and K+ for oNPG and pNPG and decreases of the Ki of both shallow and deep mode inhibitors were similar, whereas the Km and Ki of substrates and inhibitors without C6 hydroxyls remained constant. Thus, Na+ and K+ are important for binding galactosyl moieties via the C6 hydroxyl throughout catalysis. Na+ and K+ had lesser effects on the Vmax. The Vmax of pNPF and pNPA (substrates that lack a C6 hydroxyl) did not change upon addition of Na+ or K+, showing that the catalytic effects are also mediated via the C6 hydroxyl. Arrhenius plots indicated that Na+, but not K+, caused k3 (degalactosylation) to increase. Na+ also caused the k2 (galactosylation) with oNPG, but not with pNPG, to increase. In contrast, K+ caused the k2 values with both oNPG and pNPG to increase. Na+ and K+ mainly altered the entropies of activation of k2 and k3 with only small effects on the enthalpies of activation. This strongly suggests that only the positioning of the substrate, transition states, and covalent intermediate are altered by Na+ and K+. Further evidence that positioning is important was that substitution of Asp-201 with a Glu caused the Km and Ki values to increase significantly. In addition, the Kd values for Na+ or K+ were 5 to 8 fold higher. The negative charge of Asp-201 was shown to be vital for Na+ and K+ binding. Large amounts of Na+ or K+ had no effect on the very large Km and Ki values of D201N-beta-galactosidase and the Vmax values changed minimally and in a linear rather than hyperbolic way. D201F-beta-galactosidase, with a very bulky hydrophobic side chain in place of Asp, essentially obliterated all binding and catalysis.     

An efficient in vitro shoot propagation of cranberry (Vaccinium macrocarpon ait.) by axillary bud proliferation

Summary Cultures of two eranberry (Vaccinium macrocarpon Ait.) cultivars, ‘Ben Lear’ and ‘Pilgrim’, and three eranberry clones from natural stands in Newfoundland were established in a nutrient medium containing N⁶[2-isopentenyl]adenine (2iP) from nodal and/or shoot-tip explants obtained under aseptic conditions. The cultivars differed in shoot regeneration in terms of shoot number per explant with various concentrations of 2iP over two culture periods. Best total shoot production was obtained when nodal segments were cultured in the medium supplemented with 2.5–5.0 mg 2iP l⁻¹ (12.3–24.6 μM). With higher 2iP levels, shoots did not expand and had a high mortality rate. Nodal explants of the three clones cultured in the same nutrient medium supplemented with 2.5 mg 2iP l⁻¹ (12.3 μM) produced three to five healthy axillary shoots per explant. In another experiment, nodal explants were more productive than shoot tips. In all experiments with subculture, there was an increase in shoot multiplication rate for all genotypes. Shoots were rooted in vitro in the same media used for shoot proliferation, but without any growth regulators. After their transfer to potting medium, almost all of the rooted plants survived. Cranberry genotypes can be efficiently propagated and maintained through nodal culture in a nutrient medium without auxin that contains 2.5–5 mg 2iP l⁻¹ (12–25 μM).     

An independent validation study of loci associated with nematode resistance in sheep

Gastrointestinal nematode infection is a constraint on sheep production worldwide. Selective breeding programmes to enhance resistance to nematode infection are currently being implemented in a number of countries. Identification of loci associated with resistance to infection or causative mutations for resistance would enable more effective selection. Loci associated with indicator traits for nematode resistance has been identified in previous studies. In this study, Scottish Blackface, Texel and Suffolk lambs were used to validate the effects at eight genomic regions previously associated with nematode resistance (OAR3, 4, 5, 7, 12, 13, 14, 21). No SNP was significantly associated with nematode resistance at the region‐wide level but seven SNPs in three of the regions (OAR4, 12, 14) were nominally associated with trichostrongyle egg count in this study and six of these were also significant when fitted as single SNP effects. Nematodirus egg count was nominally associated with SNPs on OAR3, 4, 7 and 12.     

Filamentous fungi of the Windmill Islands, continental Antarctica. Effect of water content in moss turves on fungal diversity

This study presents the effect of water content in moss turves from the Windmill Islands, Wilkes Land, continental Antarctica on the composition of associated filamentous fungi. The two most prevalent mosses were sampled: Grimmia antarctici and Bryum pseudotriquetrum. Results were expressed as dry weights. No relationship was found between water content of the mosses or the surrounding soil and fungal diversity. Ten species of fungi were recovered and all species belong to cosmopolitan taxa. Accepted: 21 June 1999     

Birth of a Western Lowland gorilla (Gorilla gorilla gorilla) following in vitro fertilization and embryo transfer

A 21-year-old multiparous female exhibiting 31–41 day menstrual cycles was given hFSH (225 IU/day, Metrodin 75, from cycle day 3 through 9 (menses = day 1) and hCG (10,000 IU, Profasi, on day 10 to stimulate follicular development. At 35 h after hCG, under isoflurane (AErrane) anesthesia, follicles were aspirated by controlled suction under transvaginal ultrasound guidance. Metaphase II oocyctes (n = 11) were placed in modified human tubal fluid (mHTF, 100 μl) medium under oil at 37°C in humidified 5% CO₂. Frozen semen, collected by voluntary ejaculation, was thawed (70°C H₂O bath, 6 sec), diluted slowly, centrifuged, and resuspended in mHTF, and 160,000 motile spermatozoa/ml were added at 6 h after oocyte recovery. At 21 h postinsemination (p.i.) eight oocytes were at the two-cell stage, five were cryopreserved, and three were cultured to the six- to eight-cell stage in mHTF with granulosa cells before transcervical uterine transfer at 47 h p.i. using a Teflon catheter. Micronized progesterone (400 mg/d) was orally administered for 10 weeks posttransfer (p.t.). Ultrasound examination revealed a single fetus at 15 weeks p.t., and unassisted delivery of a live 1.37 kg female infant occurred at 29 weeks. Am. J. Primatol. 41:247–260, 1997. © 1997 Wiley-Liss, Inc.     

Inter-proteomic posttranslational modifications of the SARS-CoV-2 and the host proteins ‒ A new frontier

Posttranslational modification of proteins, which include both the enzymatic alterations of protein side chains and main-chain peptide bond connectivity, is a fundamental regulatory process that is crucial for almost every aspects of cell biology, including the virus-host cell interaction and the SARS-CoV-2 infection. The posttranslational modification of proteins has primarily been studied in cells and tissues in an intra-proteomic context (where both substrates and enzymes are part of the same species). However, the inter-proteomic posttranslational modifications of most of the SARS-CoV-2 proteins by the host enzymes and vice versa are largely unexplored in virus pathogenesis and in the host immune response. It is now known that the structural spike (S) protein of the SARS-CoV-2 undergoes proteolytic priming by the host serine proteases for entry into the host cells, and N- and O-glycosylation by the host cell enzymes during virion packaging, which enable the virus to spread. New evidence suggests that both SARS-CoV-2 and the host proteins undergo inter-proteomic posttranslational modifications, which play roles in virus pathogenesis and infection-induced immune response by hijacking the host cell signaling. The purpose of this minireview is to bring attention of the scientific community to recent cutting-edge discoveries in this understudied area. It is likely that a better insight into the molecular mechanisms involved may open new research directions, and thereby contribute to novel therapeutic modality development against the SARS-CoV-2. Here we briefly discuss the rationale and touch upon some unanswered questions in this context, especially those that require attention from the scientific community.     

Seasonal home range dynamics and sex differences in habitat use in a threatened,coastal marsh bird

A comprehensive understanding of spatiotemporal ecology is needed to develop conservation strategies for declining species. The king rail (Rallus elegans) is a secretive marsh bird whose range historically extended across the eastern United States. Inland migratory populations have been greatly reduced with most remaining populations inhabiting the coastal margins. Our objectives were to determine the migratory status of breeding king rails on the mid‐Atlantic coast and to characterize home range size, seasonal patterns of movement, and habitat use. Using radiotelemetry, we tracked individual king rails among seasons, and established that at least a segment of this breeding population is resident. Mean (±SE) home range size was 19.8 ± 5.0 ha (95% kernel density) or 2.5 ± 0.9 (50% kernel density). We detected seasonal variation and sex differences in home range size and habitat use. In the nonbreeding season, resident male home ranges coincided essentially with their breeding territories. Overwintering males were more likely than females to be found in natural emergent marsh with a greater area of open water. Females tended to have larger home ranges than males during the nonbreeding season. We report for the first time the use of wooded natural marsh by overwintering females. Brood‐rearing king rails led their young considerable distances away from their nests (average maximum distance: ~600 ± 200 m) and used both wooded natural and impounded marsh. King rails moved between natural marsh and managed impoundments during all life stages, but the proximity of these habitat types particularly benefitted brood‐rearing parents seeking foraging areas with shallower water in proximity to cover. Our results demonstrate the importance of interspersion of habitat types to support resident breeders. Summer draining of impounded wetlands that are seasonally flooded for wintering waterfowl allows regrowth of vegetation and provides additional habitat at a critical time for wading birds.