Nonreciprocal Interaction Research Articles

Short-term sublethal hypoxia affects a predator-prey system in northern Adriatic transitional waters

Predation intensity depends on factors that affect both the predator’s ability to locate prey as well as defensive responses by prey to approaching predators. The interactive effects of short-term hypoxia and predation were tested on the survival of two bivalves ( Tapes philippinarum and Musculista senhousia) through laboratory experiments using the crab Carcinus aestuarii as predator. We found M. senhousia to be a focal prey of C. aestuarii but, after non-lethal hypoxia, the crabs’ preference for the focal prey was influenced by the presence of the other prey, T. philippinarum. We observed an environmentally-mediated, non-reciprocal indirect interaction between the two prey species, probably caused by differences in specific traits. Identifying the influence of short-term disturbance on predator-prey relationships is critical for predicting the effects of changes in water quality on trophic interactions and food web dynamics in transitional systems.

Short-term hypoxia modulates Rapana venosa (Muricidae) prey preference in Adriatic lagoons

We studied the effect of short-term hypoxia on predation by the non-native rapa whelk (Rapana venosa) on the three most common bivalve prey in northern Adriatic lagoons: the non-native ark shell (Scapharca inaequivalvis) and Manila clam (Tapes philippinarum), and the native cockle Cerastoderma glaucum. In mesocosm experiments, bivalves were offered to predator as single prey, and as multiple choice of prey. Bivalve prey showed behavioral responses when exposed to short-term hypoxia. Under normoxia, prey were consumed in almost equal numbers when offered separately, but when choice was offered to the predator R. venosa showed a marked preference for S. inaequivalvis. Short-term hypoxia increased the vulnerability of T. philippinarum, and, consequently, rapa whelks modified their predatory behavior and switched their preference to T. philippinarum. We hypothesize this to be a case of environmentally-mediated, non-reciprocal indirect interaction between the two non-native prey species, whose causes are based upon differences in specific traits of prey. Hypoxia may facilitate the coexistence of the two non-native bivalves via predator switching. The native cockle seems the net loser of the game.

Dust clusters with non-Hamiltonian particle dynamics

The modes of clusters formed by two or three charged dust particles in a plasma are analyzed. The non-Hamiltonian dynamics of the particles is taken into account, which includes (i) nonreciprocal interaction forces due to wake effects and (ii) spatial variations of the particle charge and shielding parameters. It is shown that these effects can trigger an oscillatory instability under realistic experimental conditions. An experiment is suggested to observe this instability.

471. Chimeric Lentiviral Vectors with Safety Insurance

Lentiviral vectors as presently designed are considered to be safe. No evidence for the generation of replication competent viruses has emerged for these vectors when transduced in vitro into cultured cells. Their behavior in vivo remains to be ascertained. Their propensity to cause insertional mutagenesis, if any, is also unknown. One major safety concern is the recombination between the components of the vector system during vector production in the laboratory and with the resident virus in the clinic during therapy of individuals with apparent or non-apparent HIV infection. As an additional safety insurance, we have created chimeric or hybrid lentiviral vectors derived from HIV-1 and HIV-2. This was done for both transfer vectors and packaging constructs. Our premise was that HIV-1 and HIV-2 are dissimilar enough in sequence to curtail recombination, but similar enough to functionally complement. Our initial studies were done with HIV-2 vectors lacking the central polypurine track (PPT) and the woodchuck post-transcriptional enhancer element (WPRE), two regulatory elements reported to enhance transduction efficiency of HIV-1 vectors. This study includes HIV-2 vectors with these elements. A non-reciprocal interaction between conventional HIV-1 and HIV-2 vectors was observed in cross-packaging experiments. The titer of HIV-2 vectors was roughly the same whether packaged with the HIV-1 or HIV-2 packaging construct when titrated in cells in culture. In contrast, the titer of the HIV-1 vectors was twenty to thirty folds lower when packaged with HIV-2 than with the HIV-1 packaging construct. This could be due to the difference in the abundance of the transfer vector RNAs in the packaging cells, or due to the particular specificities of recognition and encapsidation. It was possible that the titer of HIV-1 vector was low when packaged with HIV-2 packaging construct because the Tat provided by the HIV-2 construct was poor in transactivating HIV-1 vector RNA. However, provision of additional HIV-1 or HIV-2 Tat did not change the outcome. This might imply that the reason for differential titer or non-reciprocacity lies in the interaction of the packaging signal and the gag determinants. With the chimeric packaging construct where the 'gag-pol' of the HIV-2 packaging constructs was replaced with the 'gag-pol' of HIV-1, the titer of the HIV-1 vector increased and that of the HIV-2 vector decreased relative to homologous packaging. This was not the case for the 'tat-rev' chimeric packaging constructs. However, the exchange of 'leader-gag' of HIV-1 vector with that of the HIV-2 vector in transfer vector chimeras by itself was detrimental for vector titer in both cases. These results support the possibility of creating chimeric vectors with added safety features and without sacrificing efficiency.

A model for determination of multicomponent diffusion coefficients in foods

The simultaneous diffusion of NaCl, lactic acid and water in cheese during brining, were experimentally and theoretically evaluated using multicomponent and pseudobinary mass transport models. The average concentration data of each solute in the solid at different process times were correlated with theoretical models determining the diffusion coefficients values for each solute. Applying a ternary model, main and cross diffusion coefficient values for NaCl and lactic acid showed a non-reciprocal flux interaction. The NaCl diffusion rate resulted independent of the lactic acid concentration gradient, while the lactic acid diffusion rate was increased 12 times due to NaCl concentration changes in the cheese. The results established the importance of using multicomponent mass transport models to evaluate the flux variation of solute in the global flux value.

Trans-inactivation of homologous sequences in Nicotiana tabacum.

In this chapter, we focus on a specific class of homology-dependent gene silencing, epistatic trans-inactivation, in one plant species, Nicotiana tabacum (tobacco). Epistatic trans-inactivation is defined as a nonreciprocal interaction that occurs between homologous, or partially homologous, transgenes present at nonallelic (ectopic) chromosomal locations, and the outcome is that one trans-gene locus becomes inactivated in the presence of the second (reviewed in Matzke et al. 1994b). This phenomenon possibly results from the unidirectional transmission of a hypermethylated state at one locus to a homologous unmethylated region at the second locus. There are now several examples of epistatic trans-inactivation in transgenic tobacco. We will review these cases and contrast them with other classes of homology-dependent gene silencing such as paramutation (an allelic interaction) and co-suppression/sense suppression (a reciprocal ectopic interaction). Even though the consequences of co-suppression and epistatic trans-inactivation are similar, i.e., silencing of homologous genes, they can be distinguished by a number of features, thus pointing toward fundamentally different mechanisms for the two processes. In contrast, there are notable similarities between some paramutation systems and epistatic trans-inactivation.

Observation of time-nonreversible optical interaction with zinc-blende semiconductors.

Light-induced specular rotation resulting from a time-nonreversible nonreciprocal interaction of light with semiconductors of zinc-blende structure is reported. The rotation increases with pump intensity at the rate of 1.1\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}11}$ rad ${\mathrm{W}}^{\mathrm{\ensuremath{-}}1}$ ${\mathrm{cm}}^{2}$ in GaAs and 4.3\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}11}$ rad ${\mathrm{W}}^{\mathrm{\ensuremath{-}}1}$ ${\mathrm{cm}}^{2}$ in InSb and does not disappear immediately after the end of the excitation, but partially decays on a subnanosecond time scale.

Nonreciprocal devices in integrated optics

Abstract This article reviews the solutions that have been studied for the implementation of nonreciprocal devices in integrated optics. These components, either isolators or circulators, use the nonreciprocal interaction between light and a magnetic medium. The only two isolators that have been experimented on to date are described in detail with their advantages and drawbacks, and some solutions are proposed to overcome the difficulties encountered.