Habitat and home range fidelity in a trophically dimorphic pumpkinseed sunfish (<Emphasis Type="Italic">Lepomis gibbosus</Emphasis>) population

We investigated habitat selection in a trophically dimorphic population of pumpkinseed sunfish (Lepomis gibbosus) to determine whether littoral and limnetic ecotypes exhibit habitat or site fidelity. A transplant experiment was conducted, in which 998 pumpkinseeds captured from littoral and limnetic sites were marked and released in either the site of capture, the nearest site of the same habitat type, or the nearest site of the opposite habitat type. Daily recapture attempts over the course of the reproductive and growing season provided a 25% recapture rate, 40% of which were recaptured on multiple occasions at the same site. Site fidelity was very high in both ecotypes. Results estimated with a multi-state transition model indicated that the probability of a transplanted pumpkinseed returning to its site of origin ranged from 74% for limnetic pumpkinseeds released into a different limnetic or littoral site, to 93% for littoral pumpkinseeds released into a limnetic site. Furthermore, the probability of a pumpkinseed being recaptured at its site of origin if not transplanted was estimated at 97 and 98% for limnetic individuals and littoral individuals, respectively. Discriminant Function Analysis of helminth parasite loads sampled from littoral and limnetic individuals could classify site of origin with 96–100% accuracy, suggesting that the habitat and site fidelity patterns observed with mark–recapture are indicative of long-term habitat segregation of the two forms. The results of our experiment provide compelling evidence of correlated habitat selection as a function of home range fidelity within both ecotypes of a subtly dimorphic species. Such behaviour could have a significant effect on present or future gene flow.     

Efficiency of recycled nitrogen from residues of maize (Zea mays), soybean (Glycine max) and moong (Vigna radiata) on wheat (Triticum aestivum) grain yield

Summary A laboratory incubation experiment followed by a greenhouse experiment was made in a silty clay loam at Pantnagar, India, to recycle plant utilizable N from crop residues such as maize stubble, soybean hay andmoong straw. The beneficial effect of recycled N was tested by a wheat crop. Soybean hay yielded the most NO₃–N upon mineralization and also gave the highest wheat grain yield. Maize stubble mineralized the least NO₃–N and gave the lowest grain yield.Moong straw occupied an intermediate position. An intervening period of 30–45 days would be required for the residues in question to release plant utilizable NO₃–N in sufficient quantities. From a practical view point, soybean hay appears to be an ideal choice of a residue capable of providing sufficient supplemental N for a succeding wheat crop and can be easily fitted into the prevalent cropping sequence.     

High-frequency plant regeneration through callus initiation from mature embryos of maize (<Emphasis Type="Italic">Zea Mays</Emphasis> L.)

An efficient maize regeneration system was developed using mature embryos. Embryos were removed from surface-sterilized mature seeds and sliced into halves. They were used as explants to initiate callus on induction medium supplemented with 4.0 mg l^–1 2,4-dichlorophenoxyacetic acid (2,4-D). The induction frequency of primary calli was over 90% for all inbred lines tested. The primary calli were then transferred onto subculture medium supplemented with 2.0 mg l^–1 2,4-D. Following two biweekly subcultures, embryogenic calli were formed. Inclusion of a low concentration (0.2 mg l^–1) of 6-benzylaminopurine (BA) in the subculture medium significantly promoted the formation of embryogenic callus. The addition of silver nitrate (10 mg l^–1) also supported an increased frequency of embryogenesis. The embryogenic callus readily formed plantlets on regeneration medium supplemented with 0.5 mg l^–1 BA. The regenerated plantlets were transferred to half-strength Murashige and Skoog medium supplemented with 0.6 mg l^–1 indole-3-butyric acid to develop healthy roots. The regenerated plantlets were successful on transfer to soil and set seed. Using this system, plantlets were regenerated from seven elite maize inbred lines. The frequency of forming green shoots ranged from 19.8% to 32.4%. This efficient regeneration system provides a solid basis for genetic transformation of maize.Abbreviations BA 6-Benzylaminopurine - 2,4-D 2,4-Dichlorophenoxyacetic acid - IBA Indole-3-butyric acid - KT KinetinCommunicated by M.C. Jordan     

Somatic embryogenesis in Sesbania sesban var. bicolor: A multipurpose fabaceous woody species

Somatic embryos differentiated on cotyledonary explants harvested from green pods of Sesbania sesban var. bicolor and cultured on four basal media. The best response was elicited on LS basal medium. Supplementing the LS medium with an auxin (NAA or 2,4-D) enhanced the embryogenic response. An average of 9.3 embryos developed in 23% of the cultures on 0.1 mg l^–1 NAA. The somatic embryos that developed into plantlets were transferred to soil where they have been thriving for the past 2 years.     

Use of plasmid pULB113 (RP4::Mini-Mu) to construct a genomic map ofAeromonas hydrophila

Plasmid pULB113 (RP4::Mini-Mu) promoted homologous gene transfer inAeromonas hydrophila; transfer of chromosomal markers occurred at frequencies of between 10^–3 and 10^–4 per donor cell regardless of the marker selected; this indicated chromosome transfer from multiple origins. With a variety of amino acid biosynthetic markers, a single circular map of this bacterium was constructed.     

Male Remating Behavior and Its Effect on Female Reproductive Fitness in Cnephasia jactatana Walker (Lepidoptera: Tortricidae)

Male remating behavior and its effect on the female reproductive fitness of a New Zealand leafroller, Cnephasia jactatana, were investigated in the laboratory. With a recovery period of at least 24 h between matings, most males were able to mate four times and only about 25% could mate six times during their lifespan. Only 5% of males managed to mate twice within 1 day. Mated males transferred 31–51% smaller spermatophores than virgin males. When mating with a mated male, the female was subject to a 20–51% and 23–51% reduction in fecundity and fertility, respectively. With the increasing number of matings her partner had achieved before mating with her, the female's fertility declined significantly faster than fecundity. Courtship period and mating duration remained similar regardless of the male's mating history but males required increasingly longer latency to start courtship display with the increasing number of matings achieved.     

Restoration of upland hay meadows over an 11‐year chronosequence: an evaluation of the success of green hay transfer

Grassland restoration has become a key tool in addressing the drastic losses of seminatural grassland since the mid‐twentieth century. This study examined the restoration by green hay transfer of upland hay meadows, a particularly scarce and vulnerable habitat, over an 11‐year chronosequence. The community composition of 18 restoration meadows was compared with that of donor reference sites in two study areas in the Pennine region of northern England. The study investigated: differences in community composition between donor and restoration meadows; transfer of upland hay meadow target species; and the effect of time and isolation from neighboring meadows on the community composition of the restoration meadows. Results showed that restoration meadows differed from donor meadows in that some target species were easily transferred whilst others were not found in the restoration meadows, or were at low levels of cover. Time had a significant effect on the community composition of the restoration meadows, but the similarity between restoration sites and donor sites did not increase with time, and the effect of isolation was not significant. The study showed that the green hay transfer method increases botanical diversity and is an important first step in meadow restoration. However, further restoration activity, such as seed addition, is likely to be required if restoration sites are to resemble closely the reference donor sites.     

Conjugational transfer systems of Rhodopseudomonas capsulata mediated by R plasmids

Plasmids RP1, R68.45 and RP4::Mu cts 61 were transferred into Rhodopseudomonas capsulata from Escherichia coli. The frequency of intraspecies transfer of these plasmids in R. capsulata was 10^-4–10^-5 per donor. The plasmids also mobilized chromosomal genes at a low frequency. Phototrophic recombinants from matings between recipient strains defective in the photosynthetic-apparatus and wild type donors were obtained at a frequency of 10^-7–10^-8 per donor.     

Simple sequence repeat (SSR) markers in the ectomycorrhizal fungus Laccaria bicolor for environmental monitoring of introduced strains and molecular ecology applications

Simple sequence repeat (SSR) markers were developed from SSR-enriched genome libraries for the ectomycorrhizal basidiomycete Laccaria bicolor. Seven markers were single-locus and amplified unambiguously in L. bicolor. The seven SSR markers were further characterized using an array of 15 L. bicolor strains representative of diverse origins worldwide. The observed number of alleles per locus varied from 5–9 and the values of observed heterozygosity from 0.167 to 0.667. The seven SSR loci could be amplified from DNA extracted from root tips of L. bicolor inoculated pine seedlings. All the L. bicolor ectomycorrhizas analysed exhibited the same SSR multi-locus profile as that detected for the UAMH8232 inoculant strain. The set of markers described represents a potent tool for the monitoring of introduced strains of L. bicolor and for molecular ecology applications.     

Single Turnover Kinetics of Methylation by T4 DNA-(N6-Adenine)-Methyltransferase

Interaction of T4 DNA-(N6-adenine)-methyltransferase was studied with a variety of synthetic oligonucleotide substrates containing the native recognition site GATC or its modified variants. The data obtained in the decisecond and second intervals of the reaction course allowed for the first time the substrate methylation rates to be compared with the parameters of the steady-state reaction. It was established that the substrate reaction proceeds in two stages. Because it is shown that in steady-state conditions T4 MTase forms a dimeric structure, the following sequence of events is assumed. Upon collision of a T4 MTase monomer with an oligonucleotide duplex, an asymmetrical complex forms in which the enzyme randomly oriented relative to one of the strands of the specific recognition site catalyzes a fast transfer of the methyl group from S-adenosylmethionine to the adenosine residue (k ₁ = 0.21 s^–1). Simultaneously, a second T4 MTase subunit is added to the complex, providing for the continuation of the reaction. In the course of a second stage, which is by an order of magnitude slower (k ₂ = 0.023 s^–1 for duplex with the native site), the dimeric T4 MTase switches over to the second strand and the methylation of the second residue, target. The rate of the methyl group transfer from donor, S-adenosylmethionine, to DNA is much higher than the overall rate of the T4 MTase-catalyzed steady-state reaction, although this difference is considerably less than that shown for EcoRI MTase. Base substitutions and deletions in the recognition site affect the substrate parameters in different fashions. When the GAT sequence is disrupted, the proportion of the initial productive enzyme–substrate complexes is usually sharply reduced. The flipping of the adenosine residue to be modified in the recognition site upon interaction with the enzyme, revealed by fluorescence titration, supports the existing notions about the involvement of such a DNA deformation in reactions catalyzed by various DNA-MTases.     

Energy requirements of the red kangaroo (<Emphasis Type="Italic">Macropus rufus</Emphasis>): impacts of age,growth and body size in a large desert-dwelling herbivore.

Generally, young growing mammals have resting metabolic rates (RMRs) that are proportionally greater than those of adult animals. This is seen in the red kangaroo (Macropus rufus), a large (>20 kg) herbivorous marsupial common to arid and semi-arid inland Australia. Juvenile red kangaroos have RMRs 1.5–1.6 times those expected for adult marsupials of an equivalent body mass. When fed high-quality chopped lucerne hay, young-at-foot (YAF) kangaroos, which have permanently left the mother's pouch but are still sucking, and recently weaned red kangaroos had digestible energy intakes of 641±27 kJ kg^–0.75 day^–1 and 677±26 kJ kg^–0.75 day^–1, respectively, significantly higher than the 385±37 kJ kg^–0.75 day^–1 ingested by mature, non-lactating females. However, YAF and weaned red kangaroos had maintenance energy requirements (MERs) that were not significantly higher than those of mature, non-lactating females, the values ranging between 384 kJ kg^–0.75 day^–1 and 390 kJ kg^–0.75 day^–1 digestible energy. Importantly, the MER of mature female red kangaroos was 84% of that previously reported for similarly sized, but still growing, male red kangaroos. Growth was the main factor affecting the proportionally higher energy requirements of the juvenile red kangaroos relative to non-reproductive mature females. On a good quality diet, juvenile red kangaroos from permanent pouch exit until shortly after weaning (ca. 220–400 days) had average growth rates of 55 g body mass day^–1. At this level of growth, juveniles had total daily digestible energy requirements (i.e. MER plus growth energy requirements) that were 1.7–1.8 times the MER of mature, non-reproductive females. Our data suggest that the proportionally higher RMR of juvenile red kangaroos is largely explained by the additional energy needed for growth. Energy contents of the tissue gained by the YAF and weaned red kangaroos during growth were estimated to be 5.3 kJ g^–1, within the range found for most young growing mammals.Abbreviations BMR basal metabolic rate - DEI digestible energy intake - MER maintenance energy requirement - MER_g maintenance plus growth energy requirement - PPE permanent pouch exit - RMR resting metabolic rate - YAF young-at-foot Communicated by I.D. Hume     

Zoobenthos-inhabiting Sarcotragus muscarum (Porifera: Demospongiae) from the Aegean Sea

The cavities and outer surfaces of 20 individuals of the sponge Sarcotragus muscarum collected from the Turkish Aegean coast during July–September 1993 contained a total of 148 zoobenthic species with 5299 individuals belonging to seven taxonomic groups. Among these, Polychaeta accounted for 60% of the total number of species, while Crustacea comprised 71% of the total number of individuals and 40% of the wet weight of biomass. The amphipod and decapod crustaceans Tritaeta gibbosa and Synalpheus gambarelloides, and the bivalve Hiatella arctica, were the most abundant species on the sponge samples both in terms of number of individuals and biomass values. The community structure inside the sponges was greatly influenced by the nature of the substratum around the sponge, and by the overwhelming population of the Lessepsian echinoderm Ophiactis savignyi. Number of species, biomass and diversity index values were found to be positively related to the sponge volume. Mean density and biomass of the associated taxa are 0.22 ind cm^–3 and 11.63 mg cm^–3, respectively.     

Steady-state and dynamic photosynthetic response of Adenocaulon bicolor (Asteraceae) in its redwood forest habitat

Summary The gas exchange characteristics under steadystate and transient light conditions were determined for a redwood forest understory herb Adenocaulon bicolor, that depends on use of sunflecks for a large fraction of its daily carbon gain. Measurements under steady-state conditions indicated that this species has photosynthetic characteristics that are typical for understory plants. The mean light-saturated assimilation rate was 5.26 mol CO₂ m^-2 s^-1; the light saturation and compensation occurred at 243 and 2 mol photons m^-2 s^-1, respectively. This light compensation point was much less than the photon flux density under diffuse light in the understory so that positive assimilation could be maintained throughout the day. When leaves that had been in diffuse light for at least 2 h were exposed to a sudden increase in PFD to saturating levels, 10–30 min were required for both assimilation and stomatal conductance to reach maximum values. Calculation of intercellular CO₂ pressures, however, suggest that for the first 10 min after the light increase, biochemical factors were responsible for most of the increase in assimilation. Thereafter stomatal opening caused a further increase in assimilation that was no more than 25% of the total. When fully induced leaves were returned to low light, induction was rapidly lost even though stomatal conductance decreased only slowly. This rapid loss of induction limited the capacity of A. bicolor to use sunflecks after low light periods that lasted longer than 1–2 min. However, during periods when sunflecks are more frequent there is probably little loss of induction. Under these conditions, sunflecks are used with high efficiency for assimilation.     

Mediterranean hay meadow communities: diversity and dynamics in mountain areas throughout the Iberian Central Range (Spain)

This paper reports a phytosociological study on managed hay meadow communities in the main mountains of the Spanish Central Range. Multivariate techniques (Cluster analysis and CA-ordination) were applied in the classification of the relevés and ordination of vegetation units and species. Clusters were related to the following associations: Agrostio castellanae–Arrhenatheretum bulbosi, Festuco amplae–Cynosuretum cristati, and F. amplae–Agrostietum castellanae. The scattergram suggested that the dynamic patterns between communities are associated with soil nutrient content and moisture. We propose a new subassociation: F. amplae–A. castellanae gaudinietosum fragilis that includes Salmantincensean Agrostis castellana communities growing in regions with lower supramediterranean thermotype.     

Population dynamics, reproduction, and diet of the lesser long-nosed bat (Leptonycteris curasoae) in Jalisco, Mexico: implications for conservation

We estimate fluctuations in population size and sex ratio, documentbreeding behavior and reproduction, and determine the diet of a population ofthe lesser long-nosed bat, Leptonycteris curasoae, in anisland cave in Chamela Bay, Jalisco, Mexico, with monthly sampling during anannual cycle (October 1999–October 2000). Based on the area of thecave's ceiling and wall covered with L. curasoae inrelation to the potential roost area without them, in 1999 the abundanceincreased from 80% in October to 100% in November and December. In 2000 thepopulation decreased to 80% in January, 50% in February, 30% in March, 20% inApril, 10% in May, 5% in June and July, and less than 1% in August. Thepopulation rapidly increased to 60% in September and to 80% in October.Throughout the year there were significantly more males than females; however,there was significant heterogeneity over months. In September–Novemberthere were more females, but in December–August there were more malespresent. The majority of pregnant and lactating females were observed fromDecember to March and in July, while males were reproductive fromSeptember–January and in May–June. Breeding activity was observed inthe cave in November–December. Twenty-six species of plants were consumedduring the year, based on pollen identification from fecal samples. Bombacaceousspecies were the most important component of the diet from January to May andCactaceae were most important in June–September. Peak abundance and reproductive activitycoincided with peak flower resource availability, which occurred between Octoberand January and in June–July. The year-round presence and reproductiveactivity of L. curasoae at this site throughout the yeardemonstrate that many individuals are annual residents in this area and indicatethe importance of this roosting site. In order to develop a successfulconservation program for L. curasoae, in addition toprotecting migratory corridors and northern maternity roosts, it is equallyimportant to identify and protect areas that function as breeding colonies andyear-round sanctuaries for resident populations in the south.     

Introduction of asymbiotically propagated seedlings of <Emphasis Type="Italic">Cephalanthera falcata</Emphasis> (Orchidaceae) into natural habitat and investigation of colonized mycorrhizal fungi

Asymbiotic seedling propagation and introduction of seedlings into a natural habitat were achieved for Cephalanthera falcata. For immature seeds collected 65 days after pollination, high germination rate (av. 50%) was achieved on Hyponex agar medium plates. Root development occurred in about 10% of the protocorms 5 months after seed sowing. Rooted protocorms were transferred to a culture bottle containing 100 ml of the Hyponex agar medium and incubated continually. In about 30% of the transferred individuals, shoot height reached 1.5–2 cm 8 months after the transfer. After acclimatization in wet vermiculite at 4°C for 6 months, 135 individuals were planted in a natural stand of C. falcata in mid February 2001. Shoot appearance rate was 44.4% at the first year and flowering was noted in some plants. At the fifth year, shoots with an average height of 21.6 cm still appeared in four plants, and flowering was noted in three of them. Colonization of mycorrhizal fungi was examined in two of them as well as one wild plant, in which the mycorrhizal fungi were identified to be in Thelephoraceae or Russulaceae. These fungi are known to form ectomycorrhiza with trees, and thus a tripartnership symbiosis consisting of C. falcata, mycorrhizal fungi and trees was suggested. The involvement of ectomycorrhizal fungi might be the reason for the low survival rate in the field experiment, because the distribution of ectomycorrhizal fungi relevant to this orchid is assumed to be uneven. The possibility of introducing artificially propagated orchids into natural habitats was discussed.     

Freeze or dehydrate: only two options for the survival of subzero temperatures in the arctic enchytraeid<Emphasis Type="Italic"> Fridericia ratzeli</Emphasis>

Hygrophilic soil animals, like enchytraeids, overwintering in frozen soil are unlikely to base their cold tolerance on supercooling of body fluids. It seems more likely that they will either freeze due to inoculative freezing, or dehydrate and adjust their body fluid melting point to ambient temperature as has been shown for earthworm cocoons and Collembola. In the present study we tested this hypothesis by exposing field-collected adult Fridericia ratzeli from Disko, West Greenland, to freezing temperatures under various moisture regimes. When cooled at –1 °C min^–1 under dry conditions F. ratzeli had a mean temperature of crystallisation (T_c) of –5.8 °C. However, when exposed to temperatures above standard T_c for 22 h, at –4 °C, most individuals (90%, n= 30) remained unfrozen. Slow cooling from –1 °C to –6 °C in vials where the air was in equilibrium with the vapour pressure of ice resulted in freezing in about 65% of the individuals. These individuals maintained a normal body water content of 2.7–3.0 mg mg^–1 dry weight and had body fluid melting points of about –0.5 °C with little or no change due to freezing. About 35% of the individuals dehydrated drastically to below 1.1 mg mg^–1 dry weight at –6 °C, and consequently had lowered their body fluid melting point to ca. –6 °C at this time. Survival was high in both frozen and dehydrated animals at –6 °C, about 60%. Approximately 25% of the animals (both frozen and dehydrated individuals) had elevated glucose concentrations, but the mean glucose concentration was not increased to any great extent in any group due to cold exposure. The desiccating potential of ice was simulated using aqueous NaCl solutions at 0 °C. Water loss and survival in this experiment were in good agreement with results from freezing experiments. The influence of soil moisture on survival and tendency to dehydrate was also evaluated. However, soil moisture ranging between 0.74 g g^–1 and 1.15 g g^–1 dry soil did not result in any significant differences in survival or frequency of dehydrated animals even though the apparent wetness and structure of the soil was clearly different in these moisture contents.Abbreviations DW dry weight - FW fresh weight - MP melting point - RH relative humidity - Tc crystallisation temperatures - WC water contentCommunicated by I.D. Hume     

Dogs cloned from fetal fibroblasts by nuclear transfer

Fetal fibroblasts have been considered as the prime candidate donor cells for the canine reproductive cloning by somatic cell nuclear transfer (SCNT) in regard to the future production of transgenic dogs, mainly due to their higher developmental competence and handling advantage in gene targeting. In this study, the cloning efficiency with canine fetal fibroblasts as donor cells was determined. A total of 50 presumptive cloned embryos were reconstructed, activated and transferred into the oviducts of naturally synchronous recipient bitches. While the fusion rate (76.9%) was similar to those of our earlier studies with adult fibroblasts as donor cells (73.9–77.1%), a high cloning efficiency (4.0%; 2 births/50 embryos transferred) was found compared to the previous success rate with adult fibroblasts (0.2–1.8%). The cloned beagles were healthy and genotypically identical to the donor fibroblast cells. This study shows that a fetal fibroblast cell would be an excellent donor for future production of transgenic dogs via gene targeting in this cell followed cloning using SCNT technology.     

Strengths and potential pitfalls of hay transfer for ecological restoration revealed by RAD‐seq analysis in floodplain Arabis species

Achieving high intraspecific genetic diversity is a critical goal in ecological restoration as it increases the adaptive potential and long‐term resilience of populations. Thus, we investigated genetic diversity within and between pristine sites in a fossil floodplain and compared it to sites restored by hay transfer between 1997 and 2014. RAD‐seq genotyping revealed that the stenoecious floodplain species Arabis nemorensis is co‐occurring with individuals that, based on ploidy, ITS‐sequencing and morphology, probably belong to the close relative Arabis sagittata, which has a documented preference for dry calcareous grasslands but has not been reported in floodplain meadows. We show that hay transfer maintains genetic diversity for both species. Additionally, in A. sagittata, transfer from multiple genetically isolated pristine sites resulted in restored sites with increased diversity and admixed local genotypes. In A. nemorensis, transfer did not create novel admixture dynamics because genetic diversity between pristine sites was less differentiated. Thus, the effects of hay transfer on genetic diversity also depend on the genetic make‐up of the donor communities of each species, especially when local material is mixed. Our results demonstrate the efficiency of hay transfer for habitat restoration and emphasize the importance of prerestoration characterization of microgeographic patterns of intraspecific diversity of the community to guarantee that restoration practices reach their goal, that is maximize the adaptive potential of the entire restored plant community. Overlooking these patterns may alter the balance between species in the community. Additionally, our comparison of summary statistics obtained from de novo‐ and reference‐based RAD‐seq pipelines shows that the genomic impact of restoration can be reliably monitored in species lacking prior genomic knowledge.     

Transfer of broad-host-range antibiotic resistance plasmids in soil microcosms

Broad-host-range plasmids, belonging to IncP (RP4 and pUPI102) and IncC (R57.b), were studied for intrageneric and intergeneric gene transfer in three different soil microcosms. RP4 was transferred intragenerically in clay loam, sandy loam, and sandy microcosms at frequencies of 0.71×10^–2, 0.83×10^–2, and 0.41×10^–2 respectively, optimally at 37°C and at 100% vol/wt moisture content. Under similar conditions, R57.b was also transferred at frequencies of 0.38×10^–2, 0.58×10^–2, and 0.80×10^–5 respectively at 30°C. Both RP4 and R57.b were transferred at low frequency at 20°C. Kinetics of plasmid transfer revealed that 48 h was the optimum time for intrageneric conjugal gene transfer. Gene transfer frequency was tenfold higher in all nutrient-amended soil microcosms than in the absence of nutrient amendment. RP4 was transferred to an indigenous soil bacteriumBeijerinckia indica in a nonsterile soil microcosm and to other indigenous soil bacteria, viz.Xanthomonas campestris, Azotobacter chroococcum, Acinetobacter calcoaceticus, Achromobacter agili, andRhizobium meliloti in sterile soil microcosms. pUPI102 was transferred fromA. calcoaceticus BD413 toEscherichia coli K12 J53 at a frequency of 0.75×10^–6 and 1.1×10^–6 in clay loam and sandy loam microcosms respectively. However, no gene transfer was observed in any soil microcosm when strains ofA. calcoaceticus BD413 (pUPI102) andE. coli K12 J53.2 (RP4) were used for conjugal mating. Plasmid RP4 was found to be 100% stable in all the above microorganisms.