Identification and field testing of floral odorants that attract the rove beetle <Emphasis Type="Italic">Pelecomalium testaceum</Emphasis> (Mannerheim) to skunk cabbage, <Emphasis Type="Italic">Lysichiton americanus</Emphasis> (L.)

Western skunk cabbage, Lysichiton americanus (Araceae), is pollinated mainly by the rove beetle Pelecomalium testaceum (Staphylinidae). Our objective was to determine the floral semiochemical(s) of L. americanus that attract(s) P. testaceum. Porapak Q headspace volatile extracts of L. americanus inflorescences were analyzed by gas chromatographic–electroantennographic detection (GC–EAD) and GC–mass spectrometry. In GC–EAD analyses, three floral odorants [(E)-4 nonene, (E)-5-undecene, indole] elicited consistent responses from the antennae of female P. testaceum. In field experiments, traps baited with a blend of these three components (“3-CB”) captured significantly more P. testaceum than unbaited control traps. Traps baited with the 3-CB, the two hydrocarbons, or indole, each captured significantly more beetles than unbaited control traps, indicating redundancy in the semiochemical blend. Moreover, traps baited with indole captured significantly more beetles than traps baited with either the 3-CB, or the hydrocarbons, indicating that indole is a key floral attractant for P. testaceum. Many necrophilous and coprophilous insects respond to indole in search of carrion or feces, but P. testaceum has never been associated with these types of resources. Both electrophysiological and behavioral responses of P. testaceum to two hydrocarbon semiochemicals, which are not signature odorants of carrion or feces, may indicate that the beetles recognize the odor of L. americanus as an honest signal, seek and pollinate its inflorescences, and get rewarded with pollen and on-plant mating opportunities.     

Mutualistic acacia ants exhibit reduced aggression and more frequent off‐tree movements near termite mounds

In many ant–plant mutualisms, ants establish colonies in hollow thorns, leaf pouches, or other specialized structures on their host plants, which they then defend from herbivores. Resource heterogeneity could affect the maintenance of these mutualisms if it leads to one or both partners altering their investment in the interaction. Such a phenomenon may be especially pertinent to the Acacia–ant mutualism found in East African savannas, where termite mounds have a profound effect on the spatial structuring of resources used by both plants and ants. Here, we examined whether the proximity to termite mounds of Acacia drepanolobium trees is associated with variation in the behavior of one of their ant associates, Crematogaster nigriceps. We found that ant colonies near termite mounds had decreased aggressive responses to simulated herbivory as well as increased off‐tree movement. We hypothesize that these changes are the result of resident ant colonies near termite mounds shifting investment from defense of their host plant to foraging for nearby resources.     

In vivo genome editing thrives with diversified CRISPR technologies

Prokaryotic type Ⅱ adaptive immune systems have been developed into the versatile CRISPR technology, which has been widely applied in sitespecific genome editing and has revolutionized biomedical research due to its superior efficiency and flexibility. Recent studies have greatly diversified CRISPR technologies by coupling it with various DNA repair mechanisms and targeting strategies.These new advances have significantly expanded the generation of genetically modified animal models, either by including species in which targeted genetic modification could not be achieved previously, or through introducing complex genetic modifications that take multiple steps and cost years to achieve using traditional methods. Herein, we review the recent developments and applications of CRISPR-based technology in generating various animal models, and discuss the everlasting impact of this new progress on biomedical research.     

Ablating both Fabp1 and Scp2/Scpx (TKO) induces hepatic phospholipid and cholesterol accumulation in high fat-fed mice

Although singly ablating Fabp1 or Scp2/Scpx genes may exacerbate the impact of high fat diet (HFD) on whole body phenotype and non-alcoholic fatty liver disease (NAFLD), concomitant upregulation of the non-ablated gene, preference for ad libitum fed HFD, and sex differences complicate interpretation. Therefore, these issues were addressed in male and female mice ablated in both genes (Fabp1/Scp2/Scpx null or TKO) and pair-fed HFD. Wild-type (WT) males gained more body weight as fat tissue mass (FTM) and exhibited higher hepatic lipid accumulation than WT females. The greater hepatic lipid accumulation in WT males was associated with higher hepatic expression of enzymes in glyceride synthesis, higher hepatic bile acids, and upregulation of transporters involved in hepatic reuptake of serum bile acids. While TKO had little effect on whole body phenotype and hepatic bile acid accumulation in either sex, TKO increased hepatic accumulation of lipids in both, specifically phospholipid and cholesteryl esters in males and females and free cholesterol in females. TKO-induced increases in glycerides were attributed not only to complete loss of FABP1, SCP2 and SCPx, but also in part to sex-dependent upregulation of hepatic lipogenic enzymes. These data with WT and TKO mice pair-fed HFD indicate that: i) Sex significantly impacted the ability of HFD to increase body weight, induce hepatic lipid accumulation and increase hepatic bile acids; and ii) TKO exacerbated the HFD ability to induce hepatic lipid accumulation, regardless of sex, but did not significantly alter whole body phenotype in either sex.     

Manganese uptake and toxicity in magnesium-supplemented and unsupplemented Saccharomyces cerevisiae

The magnesium content of Saccharomyces cerevisiae was found to vary by up to fivefold at differing␣ stages of batch growth and during growth in the presence of differing magnesium concentrations. Excess Mg was primarily sequestered in vacuoles. Mn²⁺-uptake experiments revealed that Mg-enriched cells had a markedly reduced capacity for Mn²⁺ accumulation. For example, after 6 h incubation in the presence of 50 μM Mn²⁺, Mn levels were approximately twofold higher in cells previously grown in unsupplemented medium than in those from Mg-supplemented medium. These differences were further accentuated at higher Mn²⁺ concentrations and were not attributable to altered cell-surface charge or altered cell-surface Mn²⁺ binding. Cellular Mg status also influenced Mn toxicity towards S. cerevisiae. During exposure to 5 mM Mn²⁺, 50% reductions in the viability of cells with initial Mg contents of approximately 1400 and 2700 nmol (10⁹ cells)⁻¹ occurred after approximately 1.6 h and 3.6 h respectively. In cells containing 3300 nmol Mg (10⁹ cells)⁻¹, more than 75% viability was still maintained after 7 h incubation with 5 mM Mn²⁺. It is concluded that Mn²⁺ uptake and toxicity in S. cerevisiae are strongly influenced by intracellular Mg, possibly through Mg-dependent regulation of divalent-cation transport activity. Received: 15 May 1996 / Received revision: 13 September 1996 / Accepted: 22 September 1996     

avr-15 encodes a chloride channel subunit that mediates inhibitory glutamatergic neurotransmission and ivermectin sensitivity in Caenorhabditis elegans.

Ivermectin is a widely used anthelmintic drug whose nematocidal mechanism is incompletely understood. We have used Caenorhabditis elegans as a model system to understand ivermectin's effects. We found that the M3 neurons of the C.elegans pharynx form fast inhibitory glutamatergic neuromuscular synapses. avr-15, a gene that confers ivermectin sensitivity on worms, is necessary postsynaptically for a functional M3 synapse and for the hyperpolarizing effect of glutamate on pharyngeal muscle. avr-15 encodes two alternatively spliced channel subunits that share ligand binding and transmembrane domains and are members of the family of glutamate-gated chloride channel subunits. An avr-15-encoded subunit forms a homomeric channel that is ivermectin-sensitive and glutamate-gated. These results indicate that: (i) an ivermectin-sensitive chloride channel mediates fast inhibitory glutamatergic neuromuscular transmission; and (ii) a nematocidal property of ivermectin derives from its activity as an agonist of glutamate-gated chloride channels in essential excitable cells such as those of the pharynx.     

Intragenic duplication and divergence in the spectrin superfamily of proteins

Many structural, signaling, and adhesion molecules contain tandemly repeated amino acid motifs. The alpha-actinin/spectrin/dystrophin superfamily of F-actin-crosslinking proteins contains an array of triple alpha-helical motifs (spectrin repeats). We present here the complete sequence of the novel beta-spectrin isoform beta(Heavy)- spectrin (beta H). The sequence of beta H supports the origin of alpha- and beta-spectrins from a common ancestor, and we present a novel model for the origin of the spectrins from a homodimeric actin-crosslinking precursor. The pattern of similarity between the spectrin repeat units indicates that they have evolved by a series of nested, nonuniform duplications. Furthermore, the spectrins and dystrophins clearly have common ancestry, yet the repeat unit is of a different length in each family. Together, these observations suggest a dynamic period of increase in repeat number accompanied by homogenization within each array by concerted evolution. However, today, there is greater similarity of homologous repeats between species than there is across repeats within species, suggesting that concerted evolution ceased some time before the arthropod/vertebrate split. We propose a two-phase model for the evolution of the spectrin repeat arrays in which an initial phase of concerted evolution is subsequently retarded as each new protein becomes constrained to a specific length and the repeats diverge at the DNA level. This evolutionary model has general applicability to the origins of the many other proteins that have tandemly repeated motifs.      

Comparisons of the molecular evolutionary process at rbcL and ndhF in the grass family (Poaceae)

We examine rate heterogeneity among evolutionary lineages of the grass family at two plasmid loci, ndhF and rbcL, and we introduce a method to determine whether patterns of rate heterogeneity are correlated between loci. We show both that rates of synonymous evolution are heterogeneous among grass lineages and that are heterogeneity is correlated between loci at synonymous sites. At nonsynonymous sites, the pattern of rate heterogeneity is not correlated between loci, primarily due to an aberrant pattern of rate heterogeneity at nonsynonymous sites of rbcL. We compare patterns of synonymous rate heterogeneity to predictors based on the generation time effect and the speciation rate hypotheses. Although there is some evidence for generation time effects, neither generation time effects nor speciation rates appear to be sufficient to explain patterns of rate heterogeneity in the grass plastid sequences.      

Kibos: A microcomputerized system for the continuous collection and analysis of behavioral data

This paper describes the design and use of an observation and recording system in which data on behavioral patterns exhibited by socially-living primates are recorded as present or absent within recurring units of time. Behavioral observations and initial editing are carried out on-line on a microcomputer. The checklist of observed behavious is open-ended and modifiable, as required by the selection of subject species and by experimental goals. Summary statistical reports are available immediately after data entry has been completed. Further editing and organization of data files take plance when data are transferred to a large computer. The virtues of this system are its ease of use by observers who can be trained rapidly, its cost-effectiveness, and its ability to record simultaneously a larger number of behaviors than other systems usually can. Included are examples of data-analytic programs which are executed after data have been transferred to a large computer.     

Adaptability of a specialist predator: the effects of land use on diet diversification and breeding performance of Verreaux's eagles

Specialist predators are generally negatively impacted by habitat change. Predators that inhabit transformed areas are usually forced to diversify their diet and this departure away from traditional resources can have negative consequences for fitness and demographic parameters. We consider this relationship as it applies to Verreaux's eagles Aquila verreauxii, which is typically considered to be a highly specialised predator of hyraxes (Procavia and Heterohyrax spp.). We investigate diet in relation to land cover in two adjacent areas of South Africa and explore the links between diet diversity, the percentage of hyrax consumed, and the breeding performance of eagles. We also examine these same patterns using data from other studies. We found that diet diversity was greater in the agriculturally developed Sandveld region compared to the natural Cederberg region. Proportions of the three main prey types were correlated with the proportion of agriculturally developed land around the nest site. Breeding performance was correlated with the diet, but not in the manner expected, with breeding productivity being greater in regions with large diet diversity and a small proportion of hyrax in the diet. We found similar patterns when placing our results into a broader geographical context using other dietary studies of Verreaux's eagles, suggesting our results were not unique to our study system. Thus, our results suggest that diet diversification does not necessarily impinge on breeding performance in the presence of adequate alternative prey resources. This research adds to the growing number of studies suggesting that some predators may be adaptable up to a threshold level of habitat transformation. These results have implications for predicting changes on such species by anthropogenic habitat transformation and highlight the potential for agriculturally developed areas to maintain a conservation value when habitat heterogeneity is maintained.