Interactions of Azospirillum spp. in soils: a review

 This review summarizes and discusses the current knowledge and the, as yet, unanswered questions on the interactions of Azospirillum spp. in bulk soil (but not in the rhizosphere). It contains sections on the isolation of these bacteria from tropical to temperate soils, and on their short- and long-term persistence in bulk soil. The interactions of these bacteria with soil particles and minerals such as clay, sand and Ca, and the effect of soil pH, soil redox potential, and the cation exchange capacity of the soil on them is demonstrated. Data is presented on the distribution of Azospirillum spp. in soils, on their production of fibrillar material essential for anchoring the cells to soil particles, on the effects of soil irrigation, and of external soil treatments, and on the effect of soil C and C used in bacterial inoculants on the cells. It shows that root exudates possibly govern bacterial motility in the soil. Finally, the effect of pesticide applications, the relationships with other soil microorganisms such as Bdelovibrio spp., Bradyrhizobium spp., and phages, and the potential use of a community-control model of Azospirillum spp. in soil and in the rhizosphere is suggested. Received: 11 November 1998     

Development of cryopreservation for maintaining yellow catfish Pelteobagrus fulvidraco sperm

Yellow catfish (Pelteobagrus fulvidraco) is a candidate freshwater fish for aquaculture in China with its high consumer demand. The aim of this study was to examine the possibility of storage of the sperm of yellow catfish by cryopreservation in liquid nitrogen. Experiments were designed to investigate the effects of the different combinations of three extenders (Ringer extender, Kurokura-1 extender and D-15 extender) and three cryoprotectants (DMSO, Glycerol and Methanol) on the cryopreservation of yellow catfish sperm. Post-thaw sperm motility, fertilization and hatching rate were detected to evaluate the reliability of sperm cryopreservation. The results demonstrated that Ringer extender and 10% methanol was the best combination for protecting the sperm during freezing in liquid nitrogen by a three-step method and thawing in a water bath at 37 °C for 60 s. In this combination for cryopreservation, sperm maintained the highest post-thaw motility (65 ± 5%), fertilization (90.47 ± 3.67%) and hatching rate (88 ± 4%). And more interestingly, the fertilization and hatching rate were similar to those of fresh sperm (97.55 ± 2.74% and 92 ± 5%). Successful sperm cryopreservation techniques for yellow catfish have been developed for hatchery purpose.     

Effect of Caffeine and Pentoxifylline Added Before or After Cooling on Sperm Characteristics of Stallion Sperm

Different additives have been tested in cooled stallion sperm, in order to maintain sperm quality and to ameliorate the decrease in sperm fertility potential. In several species, caffeine and pentoxifylline promote sperm motility by increasing energy production. We evaluate the effects of caffeine and pentoxifylline when added to stallion sperm before or after cooling. Three ejaculates from five stallions each were processed and resuspended in skim milk extender. Caffeine (5 mM), pentoxifylline (3.5 mM), or both additives combined were included to sperm before or after cooling (4°C for 24 hours). Cooled sperm were incubated at 37°C and evaluated at 0, 30, 60, and 120 minutes for motility, morphology, viability (flow cytometry), and membrane functionality (hypo-osmotic swelling test). Results were analyzed by two-factor mixed model for repeated measures and Tukey comparisons. As main effects, the caffeine and pentoxifylline affected significantly motility and kinematic parameters, without interaction between treatment and incubation after cooling. No differences were observed whether the additives were added prior or after cooling. Pentoxifylline added after cooling reduced significantly motility during incubation, but with higher values at 30 minutes. We detected a decrease in morphologically normal sperm (P < .0001), caused by an increase of tail defects (P < .003) in the presence of both additives. Viability and membrane functionality were also significantly impaired by additives. Pentoxifylline when added after cooling improved sperm motility and kinematic parameters for a short period of time. However, sperm characteristic related to fertility potential was compromised after a prolonged exposure to caffeine or pentoxifylline.     

提高牛细管冻精精子活力的试验研究

本文从细管冻精的3个关键技术环节研究了稀释液的种类对精子活力与存活的影响,确定了细管冻精精子在液氮冷冻度过冰晶期对其损伤最小的最佳熏蒸高度（最佳冷冻温度）和最佳熏蒸时间,并且对成品冷冻的细管冻精不同解冻温度及时间进行研究。由柠檬酸钠和果糖组成的稀释液精子存活时间长,Tris稀释液冷冻后精子活力高于其他配方;牛细管冻精最佳熏蒸距离为2cm,时间影响不显著,7~9min均可;用50℃温水15s解冻精子的活力最高。     

Effects of α2-adrenergic drugs on small intestinal motility in the horse: An in vitro study

The effects of selective α₂-agonists (xylazine, detomidine and medetomidine) and antagonists (yohimbine and atipamezole) on in vitro small intestine motility in the horse were evaluated. Samples of equine jejunum were placed in isolated organ baths and drug-induced modifications of motility were measured by means of an isotonic transducer. All tested α₂-agonists dose-dependently reduced both spontaneous and electrically-evoked phasic contractions. Conversely, α₂-antagonists were ineffective when tested alone, and showed a heterogeneous and dose-independent ability to inhibit agonist activity. In particular, the antagonism exerted by higher concentrations of both yohimbine and atipamezole against α₂-agonists was weaker than when lower concentrations were used. The data are indicative of the presence of both pre- and post-synaptic α₂-adrenoceptors with inhibitory activity on equine jejunum motility, and support a possible therapeutic utility of these drugs in horse intestinal disorders associated with hypermotility.     

Myoelectric activity in the intestine of cows with strangulating obstruction of the distal small intestine

Myoelectric activity in 2 cows instrumented with permanent electrodes in the ileum, cecum, proximal loop of the ascending colon (PLAC), and spiral colon was analyzed after an obstruction developed in the distal small intestine. Results were compared with patterns from a group of 7 normal cows. Myoelectric activity in the ileum immediately orad to the occlusion was characterized by abolition of the migrating myoelectric complex (MMC) and a constant pattern of strong spike bursts of long duration. Cyclic activity was present in all parts of the large intestine, and propagation of phase III activity was evident from proximal to distal. A slight degree of disorganization in phase III propagation was restricted to the spiral colon. Activity cycles tended to be shorter in the cecum and PLAC of both cows with colic than in normal cows, and the intensity of spiking activity was generally lower. Changes in duration of the MMC in the spiral colon (bovine colonic MMC, bcMMC) were inconsistent, but the intensity of spiking activity tended to be lower in phases I and II of both cows compared to controls. The organization of phase III in several spindles typical of the bovine spiral colon was not disrupted, but phase IV of the bcMMC occurred only infrequently. Organized cyclic activity occurred in the large intestine of both cows despite complete disruption of the small intestinal MMC, indicating the presence of mechanisms able to initiate and regulate coordinated myoelectric patterns in the large intestine independent of the small intestine.     

Intravenous lidocaine and small-intestinal size,abdominal fluid,and outcome after colic surgery in horses

Twenty-eight horses with the diagnosis of an intestinal disorder requiring surgical intervention were randomly assigned to lidocaine (n = 13) or saline (control, n = 15) treatment groups. After induction of anesthesia, treated horses received a loading dose of 2% lidocaine (0.65 mg/kg) intravenously, followed by a continuous rate of infusion of 1% lidocaine (0.025 mg/kg/min) until the discontinuation of anesthesia. Upon recovery from anesthesia, a 2nd loading dose of 2% lidocaine (1.3 mg/kg) was administered, followed by an infusion of 1% lidocaine (0.05 mg/kg/min) for 24 hours postoperatively. The control group received equivalent volumes of saline. Lidocaine-treated horses had significantly better minimum jejunal cross-sectional area scores (P = .011), minimum jejunal diameter scores (P = .002), and intestinal ultrasound index (IUI) (P = .007). Peritoneal fluid was detected by percutaneous ultrasound examination in 8 of the 15 control animals but in none of the treated animals (P = .003). Failure to obtain fluid via abdominocentesis was significantly more frequent for lidocaine-treated horses (P = .025). No significant differences between the groups were found in the presence of gastrointestinal sounds, time to passage of 1st feces, number of defecations in the 1st 24 hours, presence of gastric reflux, duodenal or jejunal wall thickness, maximum duodenal or jejunal diameter or cross-sectional area, minimum duodenal diameter or cross-sectional area, duodenal and jejunal intraluminal echogenicity, small-intestinal contractions per minute, rate of complications, or outcome. On the basis of this study, lidocaine infusion may have some desirable effects on jejunal distension and peritoneal fluid accumulation and was well tolerated perioperatively in horses with colic. The low incidence of small-intestinal lesions and gastric reflux in the study makes it difficult to assess the use of lidocaine in the prevention of postoperative ileus (POI).     

Characterization of Senegalese sole, Solea senegalensis, male broodstock in terms of sperm production and quality

Sperm quality and production have never been characterized in Solea senegalensis males. Reproduction in captivity in this species has been obtained mostly with wild-captured animals, because it is common that the F1 generation fails to reproduce. However, there is no information on sperm quality from both types of broodstocks. The aim of the present study was to characterize sperm production and to describe the profiles of spermiation in individual wild-captured males. Also, sperm quality and production were determined in two types of broodstocks established in our facilities; wild-captured and F1 individuals. The males were analyzed for their fluency and identified as fluent or non-fluent. The sperm volume, cell concentration, sperm production and motility were recorded from mid February until mid November in both broodstocks. Results showed that S. senegalensis males can produce motile sperm during all this period, with specific peaks of high spermiation and a high percentage of fluent males. This fact was observed in both male broodstocks. There was a large variability in terms of sperm profiles in males maintained under the same conditions. Sperm volume collected in this species was very small and ranged from 5 to 20 μl in F1 broodstock and 10 to 80 μl in wild-captured broodstock. Cell density ranged from 0.7 to 1.2 × 10⁹ spermatozoa/ml in F1 males to values of 1-2 × 10⁹ spermatozoa/ml for the wild-captured males. Sperm production (total spermatozoa per stripping) was also very low and ranged from 20 × 10⁶ spermatozoa for F1 broodstock to 40-60 × 10⁶ spermatozoa for wild-captured broodstock. Our results demonstrated that sperm production in this species is very low and variable according to the type of males. These results suggest that a previous selection of males according to their fluency, sperm production and provenience (wild-captured or F1) should be taken into account in the establishment of a S. senegalensis broodstock.     

Quantity, motility and fertility of tench Tinca tinca (L.) sperm in relation to LHRH analogue and carp pituitary treatments

The spermiation of tench males was stimulated with Supergestran containing mammalian LHRHa lecireline at the following doses: 5, 10, 20 and 40 g kg⁻¹ b.w.; then with carp pituitary suspension (CPS) at a dose of 2 mg kg⁻¹ b.w. and with a control of saline physiological solution. The following days, meaning 24, 48 and 72 h after injection, sperm was collected to evaluate volume and the number of sperm per male per kg body weight (B.W.) The percentage of motile sperm and velocity of spermatozoa were measured 48 h after hormonal injection, and 72 h after hormonal injection the sperm was evaluated for fertilization and hatching ability. All 42 males in experimental groups were diploid. Live weight did not differ significantly among experimental groups. The strongest stimulation of spermiation was achieved with LHRHa in dosage of 20 and 40 g kg⁻¹ b.w. and CPS compared to males of the control group and lower dosage of LHRHa. Analysis of variance showed no significant influence of the treatment on the velocity and percentage of motile spermatozoa. The effect of different treatment on the fertilization capacity (the number of spermatozoa per egg was equilibrated) was significant. Significantly the highest quality of sperm collected 72 h after injection expressed by percentage of fertilization and hatching (62–65% fertilization and 61–64% hatching rates, respectively) was found for LHRHa in dosage of 20 and 40 g kg⁻¹ b.w. Significantly the lowest parameters of fertilization and hatching were found for the control group, on the 12% level.