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Plant lock and ant key: pairwise coevolution of an exclusion filter in an ant-plant mutualism.

Although observations suggest pairwise coevolution in specific ant-plant symbioses, coevolutionary processes have rarely been demonstrated. We report on, what is to the authors' knowledge, the strongest evidence yet for reciprocal adaptation of morphological characters in a species-specific ant-plant mutualism. The plant character is the prostoma, which is a small unlignified organ at the apex of the domatia in which symbiotic ants excavate an entrance hole. Each myrmecophyte in the genus Leonardoxa has evolved a prostoma with a different shape. By performing precise measurements on the prostomata of three related myrmecophytes, on their specific associated ants and on the entrance holes excavated by symbiotic ants at the prostomata, we showed that correspondence of the plant and ant traits forms a morphological and behavioural filter. We have strong evidence for coevolution between the dimensions and shape of the symbiotic ants and the prostoma in one of the three ant-Leonardoxa associations.

Animals↗

Forest edges and fire ants alter the seed shadow of an ant-dispersed plant.

Exotic species invade fragmented, edge-rich habitats readily, yet the distinct impacts of habitat edges and invaders on native biota are rarely distinguished. Both appear detrimental to ant-dispersed plants such as bloodroot, Sanguinaria canadensis. Working in northeastern Georgia (USA), an area characterized by a rich ant-dispersed flora, fragmented forests, and invasions by the red imported fire ant, Solenopsis invicta, I monitored the interactions between ants and S. canadensis seeds in uninvaded forest interiors, uninvaded forest edges, invaded forest interiors, and invaded forest edges. I observed 95% of the seed dispersal events that occurred within the 60-min observation intervals. Seed collection rates were similar among all four (habitat x invasion) groups. The presence of invasive ants had a strong effect on seed dispersal distance: S. invicta collected most seeds in invaded sites, but was a poorer disperser than four of five native ant taxa. Habitat type (interior versus edge) had no effect on seed dispersal distance, but it had a strong effect on seed dispersal direction. Dispersal towards the edge was disproportionately rare in uninvaded forest edges, and ants in those habitats moved the average dispersed seed approximately 70 cm away from that edge. Dispersal direction was also skewed away from the edge in uninvaded forest interiors and invaded forest edges, albeit non-significantly. This biased dispersal may help explain the rarity of myrmecochorous plants in younger forests and edges, and their poor ability to disperse between fragments. This is the first demonstration that forest edges and S. invicta invasion influence seed dispersal destination and distance, respectively. These forces act independently.

Animals↗

Effects of aromatic cedar mulch on the Argentine ant and the odorous house ant (Hymenoptera: Formicidae).

In laboratory studies, the Argentine ant, Linepithema humile (Mayr), and the odorous house ant, Tapinoma sessile (Say), avoided aromatic cedar mulch as a nesting substrate. Both ant species were killed when confined with fresh aromatic cedar mulch in sealed containers. However, when confined with cedar mulch that had been aged outdoors for up to 140 d, mortality of L. humile was complete regardless of mulch age, whereas T. sessile mortality declined significantly over the mulch-aging period. Argentine ant susceptibility to aromatic cedar mulch was also greater than that of the odorous house ant when colonies were restricted to mulch in open trays. In addition, commercial aromatic cedar oil was lethal to both ant species. Our results suggest that aromatic cedar mulch may serve as an effective component of a comprehensive urban ant management program.

Animals↗

Invasive Argentine ants (Linepithema humile) do not replace native ants as seed dispersers of Dendromecon rigida (Papaveraceae) in California, USA.

We investigated the indirect effects of Argentine ant (Linepithema humile) invasions on patterns of seed dispersal and predation in the myrmecochorous tree poppy Dendromecon rigida in coastal San Diego County, California. Significantly more seeds were removed from ant-accessible seed stations at sites numerically dominated by a common harvester ant (Pogonomyrmex subnitidus), a native disperser of these seeds and a species sensitive to displacement by L. humile, than from those stations at sites where L. humile was in the majority. Predation of seeds was high, but variable, across sites, suggesting that reduced dispersal could result in increased seed predation in some habitats. Removal of elaiosomes did not affect the frequency with which predators removed seeds, but ants removed significantly more seeds with elaiosomes than without. In behavior trials, only P. subnitidus was able to carry seeds of Dendromecon rigida effectively. L. humile and a small native ant species, Dorymyrmex insanus, while displaying interest in the diaspores, were seldom able to carry whole seeds and, when they did, only carried them a few centimeters. Displacement of native harvester ants by L. humile appears to decrease the dispersal of Dendromecon rigida seeds and may be increasing loss of seeds due to predation.

Animals↗

Imported fire ant hypersensitivity. Studies of human reactions to fire ant venom.

It is now apparent that venom and venom components of the Hymenoptera superfamilies of Apida (honeybee) and Vespida (wasps, yellow jackets, and hornets) are becoming increasingly important in the diagnosis and treatment of hypersensitivity reactions. Stings from fire ants (superfamily Formicidae, family Myrmicinae) have also been recognized as causes of systemic reactions in man. Fire ant venom is unique in its composition, consisting mainly of alkaloids in aqueous suspension with only trace amounts of protein. This study compares the skin reactivity of fire ant venom and synthesized alkaloid components with the whole body extract (WBE) of fire ants and other Hymenoptera. The venom as well as the WBE of fire ants was found useful for skin test diagnosis of sensitive individuals. There appear to be cross-reactive or shared antigens between fire ant venom, WBE, and WBE of other Hymenoptera. Successful passive transfer of skin reactivity to nonsensitive individuals was accomplished with sera from sensitive individuals. Loss of this passive transfer by heating sera at 56 degrees C for 4 hr is evidence in favor of IgE mediating the positive skin test to the venom.

Animals↗

Occurrence of Myrmicinosporidium durum in red imported fire ant, Solenopsis invicta, and other new host ants in eastern United States.

Myrmicinosporidium durum, a parasitic fungus in several ant species, is reported from seven new hosts collected in the eastern United States, including Solenopsis invicta, Solenopsis carolinensis, Paratrechina vividula, Pheidole tysoni, Pheidole bicarinata, Pyramica membranifera, and Pogonomyrmex badius. Spores can be found in most ant body parts, are dark brown when mature, and clear to light brown while immature. Ants infected with mature spores appear darker than normal. Spores from different hosts were 47-57 microm in diameter. Prevalence in host populations varied between 2 and 67% of the ants, and 3-100% of the colonies. Infection was most common in S. carolinensis with prevalence rates between 22 and 67%. Prevalence rates for S. invicta individuals were lower than for other ants, however, prevalence rates within the infected colonies were as high as 31%. Observations of disease were recorded mostly from late summer and fall. Possible implications of this new disease in red imported fire ants are discussed.

Animals↗

Dracula ant phylogeny as inferred by nuclear 28S rDNA sequences and implications for ant systematics (Hymenoptera: Formicidae: Amblyoponinae).

Ants are one of the most ecologically and numerically dominant families of organisms in almost every terrestrial habitat throughout the world, though they include only about 1% of all described insect species. The development of eusociality is thought to have been a driving force in the striking diversification and dominance of this group, yet we know little about the evolution of the major lineages of ants and have been unable to clearly determine their primitive characteristics. Ants within the subfamily Amblyoponinae are specialized arthropod predators, possess many anatomically and behaviorally primitive characters and have been proposed as a possible basal lineage within the ants. We investigate the phylogenetic relationships among the members of the subfamily, using nuclear 28S rDNA sequence data. Outgroups for the analysis include members of the poneromorph and leptanillomorph (Apomyrma, Leptanilla) ant subfamilies, as well as three wasp families. Parsimony, maximum likelihood, and Bayesian analyses provide strong support for the monophyly of a clade containing the two genera Apomyrma+Mystrium (100% bpp; 97% ML bs; and 97% MP bs), and moderate support for the monophyly of the Amblyoponinae as long as Apomyrma (Apomyrminae) is included (87% bpp; 57% ML bs; and 76% MP bs). Analyses did not recover evidence of monophyly of the Amblyopone genus, while the monophyly of the other genera in the subfamily is supported. Based on these results we provide a morphological diagnosis of the Amblyoponinae that includes Apomyrma. Among the outgroup taxa, Typhlomyrmex grouped consistently with Ectatomma, supporting the recent placement of Typhlomyrmex in the Ectatomminae. The results of this present study place the included ant subfamilies into roughly two clades with the basal placement of Leptanilla unclear. One clade contains all the Amblyoponinae (including Apomyrma), Ponerinae, and Proceratiinae (Poneroid clade). The other clade contains members from subfamilies Cerapachyinae, Dolichoderinae, Ectatomminae, Formicinae, Myrmeciinae, and Myrmicinae (Formicoid clade).

Animals↗

Occurrence of aminoglycoside-modifying-enzyme genes aac(6')-aph(2"), aph(3'), ant(4') and ant(6) in clinical isolates of Enterococcus faecalis resistant to high-level of gentamicin and amikacin.

The genes coding for 4 aminoglycoside-modifying enzymes AAC(6')-APH(2"), APH(3'), ANT(4') and ANT(6) were determined in 44 Slovak clinical isolates of Enterococcus faecalis with high-level resistance to gentamicin (HLGR, collection 1) and 48 E. faecalis isolates with resistance to amikacin (AR, collection 2). The occurrence of spotted genes was (collection 1 vs. collection 2): aac(6)-aph(2") 81.8 vs. 8.3 %, ant(4') 52.3 vs. 81.3 %, aph(3') 50 vs. 56.3 % and ant(6) 6.8 vs. 4.2 %, the most frequent combinations of genes in the HLGR collection were aac(6')-aph(2") + ant(4') and aac(6')-aph(2") + aph(3). In contrast, the aph(3') + ant(4') gene profile was predominant in AR isolates. None of the isolates contained all four AGME genes simultaneously.

Acetyltransferases↗

Safety and efficacy of fire ant venom in the diagnosis of fire ant allergy.

Thirty-three adult patients who had had systemic allergic reactions to fire ant stings and 33 insect-nonallergic control subjects were skin tested with single lots of Solenopsis invicta (Sol i) fire ant venom (IFAV) and two commercially available imported fire ant whole body extracts (IFA WBEs). All three extracts were analyzed for protein concentration. Sol i II and Sol i III concentrations were each assayed by means of two ELISAs with complementary monoclonal antibodies, one species specific and one cross-reactive. Radioallergosorbent test (RAST) to IFAV and both IFA WBEs was performed on sera from all study subjects. Both IFA WBEs contained high concentrations of fire ant body proteins. Sol i II and III concentrations each varied twofold between the two IFA WBE preparations. Patients were generally more reactive to IFAV than IFA WBE by skin testing and RAST. IFAV RAST appeared to be a more sensitive assay than IFA WBE RAST. No adverse reactions occurred to skin testing with IFAV, but intradermal testing with higher concentrations of IFA WBE caused delayed large local reactions in 16 of 30 (53%) control subjects. These reactions were attributed to the large amounts of extraneous body proteins in IFA WBE. These results (1) demonstrate that skin testing with IFAV is safe, (2) indicate that IFAV is more potent than IFA WBE, and (3) suggest that IFAV may be the superior reagent for diagnosis of fire ant allergy.

Adult↗

Interaction between ants and fruits of Guapira opposita (Nyctaginaceae) in a Brazilian sandy plain rainforest: ant effects on seeds and seedlings.

This study examines the dispersal system of Guapira opposita in a tropical sandy rainforest in southeast Brazil. Guapira trees produce small fruits with a high protein content (28.4%) and low lipid content (0.3%), and the plant is primarily dispersed by birds. Mature fruits of G. opposita can fall spontaneously with the pulp intact, or be dropped by birds with bits of pulp attached. In either case, ground-dwelling ants rapidly remove the fruits to their nest (93% after 12 h). The ponerine ants Odontomachus chelifer and Pachycondyla striata are the main seed vectors among the ants, and together account for 56% (20 of 36) of the ant-fruit interactions recorded on the forest floor. Individual workers of O. chelifer and P. striata transport single fruits to their nests. Bits of pulp are fed to larvae and worker nestmates, and intact seeds are discarded outside the nest. Germination success in Guapira is higher for cleaned seeds (pulp removed) than for seeds coated by pulp. Guapira seedlings and juveniles are more frequent close to Odontomachus nests than at sites without such nests. Soil samples from Odontomachus nests had greater penetrability, and higher concentrations of P, K, and Ca than random soil samples. Field experiments suggest that the association between G. opposita seedlings and O. chelifer nests can potentially render the plant some protection against herbivores. Results indicate that fruit displacement by ponerine ants play an important role in the biology of G. opposita seeds and seedlings in the sandy forest, and illustrate the complex nature of the dispersal ecology of tropical tree species.

Animals↗

In vivo and in vitro comparison of fire ant venom and fire ant whole body extract.

Thirty-four patients with a history of immediate hypersensitivity to the sting of the imported fire ant were evaluated in a study designed to compare the diagnostic usefulness of fire ant whole body extract (WBE) preparations with that of fire ant venom (IFAV). Ninety-one percent (31/34) of the hypersensitive patients skin tested with IFAV at a maximal concentration of 1:5 X 10(3), v/v, demonstrated a wheal equal to or greater than the histamine control. Fifty-three percent (18/34) of the group were skin test positive to a WBE preparation. When the criteria for a positive skin test were relaxed, 82% of the hypersensitive group could be identified with the IFAWBE. A comparison of skin test results in sensitive patients revealed variability in the sensitivity of the WBE preparations utilized in the study. Leukocyte histamine release demonstrated a dose-response release of histamine with both IFAV and SIWBEa preparations. Specific venom antisera produced in rabbits identified a precipitin line of common identity in a gel-diffusion system containing IFAWBE and IFAV. This finding was verified by the competitive inhibition of IFAWBE with IFAV in a solid-phase radioimmunoassay system. Fire ant WBEs contain venom constituents and are effective diagnostic agents in up to 82% of patients with hypersensitivity to the sting of the imported fire ant. Marked variability in the responsiveness of sensitive patients to different WBE preparations mandates standardization of these diagnostic preparations.

Adolescent↗

Formicitylenchus oregonensis n. g., n. sp. (Allantonematidae: Nematoda), the first tylenchid parasite of ants, with a review of nematodes described from ants.

The first tylenchid parasite of ants, Formicitylenchus oregonensis n. g., n. sp., is described from a queen carpenter ant Camponotus vicinus Mayr in Western Oregon, USA. The new genus is characterised by the excretory pore anterior to the nerve-ring and rounded tails in the free-living adults, a stylet bearing basal thickenings in the free-living female, a smaller stylet lacking basal thickenings in the male and a short, crenulate leptoderan bursa. The mature parasitic female is light yellow and ovoviviparous. F. oregonensis n. sp. is closely related to members of Metaparasitylenchus Wachek, 1955, with species parasitising beetles living under bark or in rotten wood, a habitat similar to that of carpenter ants. However, males of Metaparasitylenchus are characterised by a fairly long tail with a broad peloderan bursa. It is suggested that this case of tylenchid parasitism in ants is an example of environmental host selection. A review of the described nematode parasites of ants is presented.

Abdomen↗

Path integration in desert ants, Cataglyphis: how to make a homing ant run away from home.

Path integration is an ant's lifeline on any of its foraging journeys. It results in a homebound global vector that continually informs the animal about its position relative to its starting point. Here, we use a particular (repeated training and displacement) paradigm, in which homebound ants are made to follow a familiar landmark route repeatedly from the feeder to the nest, even after they have arrived at the nest. The results show that during the repeated landmark-guided home runs the ant's path integrator runs continually, so that the current state of the homebound vector increasingly exceeds the reference state. The dramatic result is that the homing ants run away from home. This finding implies that the ants do not rely on cartographic information about the locations of nest and feeder (e.g. that the nest is always south of the feeder), but just behave according to what the state of their egocentric path integrator tells them.

Animals↗

Apolipoprotein E and other cerebrospinal fluid proteins differentiate ante mortem variant Creutzfeldt-Jakob disease from ante mortem sporadic Creutzfeldt-Jakob disease.

The ability to perform an ante mortem differential diagnosis of Creutzfeld-Jakob disease (CJD) is aided by several clinical and molecular tests. There is a need for molecular tests which can reliably distinguish ante mortem variant CJD (vCJD) from ante mortem sporadic CJD (spCJD). A proteomics approach employing two-dimensional protein electrophoresis is applied to the study of ante mortem CSF samples obtained in collaboration with the CJD Surveillance Unit and the National Hospital for Neurology and Neurosurgery. The sample set includes two cases of vCJD, three cases of spCJD and three neurologic controls. Preliminary data using a panel of seven molecular markers is able to distinguish vCJD from spCJD using a heuristic clustering algorithm. One of the molecular markers has been identified as apolipoprotein E which appears to be upregulated in the cerebrospiral fluid (CSF) of patients with vCJD as compared to spCJD. Analysis of ante mortem CSF may help to differentiate patients with vCJD from those patients with spCJD.

Adult↗

Imported fire ants: the ants from hell!

Imported fire ants may certainly be considered the ANTS FROM HELL! This review focuses on both the interesting entomology of fire ants and the important medical characteristics of fire ant stings. They sting and they kill; they destroy; they mate in mid-air; and we may not be able to stop them. However, although they inject extremely potent venom, individuals can prevent secondary infections by leaving the so-called pustules alone and not opening them. Individuals who suffer systemic reactions may receive adequate treatment with the whole body extract immunotherapy.

Adolescent↗

Survey of fatal anaphylactic reactions to imported fire ant stings. Report of the Fire Ant Subcommittee of the American Academy of Allergy and Immunology.

A physician questionnaire survey was conducted by the Fire Ant Subcommittee of the American Academy of Allergy and Immunology to document deaths caused by imported fire ant stings. From the 29,300 physicians surveyed, reports of 83 fatal and two near-fatal fire ant-sting reactions were received. Most anaphylactic deaths were reported from Florida (22) and Texas (19). After excluding duplicate reports, four confirmed deaths were documented in Alabama, 10 in Florida, two in Georgia, two in Louisiana, and 14 in Texas.

Adult↗

The mitochondrial phase of the glucocorticoid-induced apoptotic response in thymocytes comprises sequential activation of adenine nucleotide transporter (ANT)-independent and ANT-dependent events.

In thymocytes, dexamethasone initiates cytochrome c-dependent processing of caspase-9 and the activation of caspase-3 to trigger apoptotic damage. Using murine thymocytes or a thymocyte cell line WEHI 7.1, we show that this pathway is inhibited by dominant-negative caspase-9, the anti-apoptotic protein Bcl-2, or by blocking components of the mitochondrial permeability transition pore complex (PTPC). We use DIDS (dithiocyanatostilbene-2,2-disulfonic acid), a pharmacological modifier of VDAC (voltage-dependent anion channel) function or ectopic expression of hexokinase-II, to examine the role of the VDAC--a mitochondrial outer membrane protein--in this apoptotic pathway. This approach implicated the VDAC in dexamethasone-mediated cytochrome c release, processing of caspase-9 and caspase-3, the loss of mitochondrial transmembrane potential (Deltapsim), nuclear damage and cell lysis. Inhibiting the adenine nucleotide transporter (ANT), a protein on the mitochondrial inner membrane, also blocks dexamethasone-induced apoptosis, but the ANT regulates caspase-3 processing and nuclear damage but not the mitochondrial efflux of cytochrome c. Collectively, the data identify two separable, but connected events in dexamethasone-induced mitochondrial damage in thymocytes. The first event is an increase in permeability of the mitochondrial outer membrane leading to VDAC-regulated efflux of cytochrome c and initial processing of caspase-9 followed by ANT-dependent caspase-3 processing and apoptotic damage to cells.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗

Binding mode of 2-amino-5-nitrothiazole (ANT) in platinum complexes, trans-[PtCl2(ANT)2], affects DNA binding, toxicity and radiosensitizing ability.

The radiosensitizer 2-amino-5-nitrothiazole (ANT) can react with platinum to form many products because of the availability of two potential nitrogen donors as ligands for metals. Two of these complexes, both with two ANT molecules in the trans configuration, differ because of their linkages. In the first, Pt is bound to ANT via the amine group (A) and in the second via the thiazole ring nitrogen (R). Isomer R is a better radiosensitizer than A in hypoxic Chinese hamster ovary cells, giving enhancement ratios of 1.6 versus 1.15 with 100 mumol dm-3 complex. The ring-bound isomer also exhibits higher toxicity than the amine bound in air and under conditions of hypoxia. Sensitization by isomer R is much higher under conditions of hypoxia than in air. In an assay to assess DNA binding, isomer R inhibited restriction enzyme cleavage of DNA but isomer A did not (up to 6 h at 300 mumol dm-3). It appears from this study on two very similar complexes that the complex which exhibits stronger binding may be targetting the radiosensitizer to the DNA, resulting in greatly improved sensitization.

Animals↗