阿拉善黄鼠的生命表及繁殖

将采自野生种群的阿拉善黄鼠(Spermophilus dauricus alaschanicus Buechner)( 下称黄鼠)样本划分为8个年龄间隔,然后编制生命表。结果表明,黄鼠的平均死亡率(qx)为0.7512(♂)和0．6222(♀),平均寿命为1.3311年(♂)和1.1073年(♀)。0-l岁龄黄鼠的期望寿命(ex)为0.8311年(♂)和1.1073年(♀)。世代净增殖率(R_o)每代为l.7327。种群内禀增长率(瞬时)(r_m)为0.1433,世代平均时间(T)为3.8346年,周限增长率(r)为1.1541/年。     

辽西义县组孢粉植物群指示的古气候条件

迄今为止,在辽西北票义县地区的下白垩统义县组二段沉积层中,已发现孢粉化石62属,82种,藻类化石3种。本文对产于不同地点沉积层中的孢粉化石进行了系统研究和总结。根据孢粉母体植物形态和生态特征、生长的气候环境和干湿度环境,对义县组二段的孢粉植物群进行了植被类型、气候带类型和干湿度类型的统计和划分,认为义县组二段沉积时期,其孢粉植被类型为针叶林,所处的气候环境为湿润的亚热带一暖温带。由于植被成分中存在落叶阔叶植物和旱生植物,推测气候环境存在季节性变化,间有干旱一半干旱气候条件。     

Influence of sodium dodecyl sulfate/TritonX-100 micelles on the oxidation of D-fructose by chromic acid in presence of HClO(4)

The kinetics of oxidation of D-fructose by chromic acid in aqueous and aqueous surfactant (sodium dodecyl sulfate, SDS, and alkylphenyl polyethylenglykol, TX-100) media have been investigated in the presence of HClO(4). The reaction is acid catalyzed and is associated with an induction period which is dependent on [H(+)], [surfactant] and temperature. The order of oxidation during induction under [D-fructose]>[chromic acid] conditions is fractional in each reagent in both media. The rate constant was found to increase with [Mn(II)]. A mechanism has been proposed for the reaction. The micelles produce a catalytic effect in the range of SDS and TX-100 concentrations used, and the effect is explained by means of the pseudo-phase mass-action model. In the presence of SDS, the reaction is inhibited by electrolytes (NH(4)Br, NaBr, LiBr), and the inhibition order Na(+)>Li(+)>NH(4)(+) is explained on the basis of electrostatic considerations. The rate constant (k(m)), binding constants (K(S) and K(F)), and corresponding activation parameters (E(a), delta H( not equal ) and delta S( not equal )) have been evaluated and discussed. The order of reactivities of different sugars is found as: D-fructose>D-arabinose>D-xylose approximately D-glucose.     

浙江汉族人群细胞因子基因多态性分析

为了探讨浙江汉族人群13种细胞因子基因多态性的分布情况, 采用PCR-SSP对100名汉族人群的IL-1α(T/C-889)、IL-1β(C/T-511, T/C+3962)、IL-1R(C/T Pst-I 1970)、IL-1RA(T/C Mspa1-I 1100)、IL-2 (T/G -330, G/T +166)、IL-4 (T/G -1098, T/C -590, T/C -33)、IL-4Rα(G/A +1902)、IL-6 (G/C-174, G/A nt565)、IL-10 (G/A -1082, C/T -819, C/A-592)、IL-12(C/A -1188)、gIFN (A/T UTR 5644)、TGFβ(C/T codon 10, G/C codon 25)、TNFα(G/A -308, G/A -238)等细胞因子基因多态性进行分型。结果显示, (1)在检测的13种细胞因子中, TGF(G codon 25)等位基因频率为1.00, 未检测到TGF(C codon 25)等位基因; (2)细胞因子等位基因频率大于0.95的有IL-1α(C-889)、IL-1β(C +3962)、IL-4 (T –1098)、IL-6 (G-174)、IL-6(G nt565)、IL-10(A –1082)和TNFa (G -238); 频率低于0.05的有IL-1α(T -889)、IL-1β(T +3962)、IL-4(G –1098)、IL-6 (A-174)、IL-6 (A nt565)、IL-10 (G –1082) 和TNFa (A -238); (3) IL-10高表达单倍型GCC频率为0.05, 低表达单倍型ATA频率为0.735; TGF β高表达单倍型TG频率为0.49, 低表达单倍型CC频率为0; TNF a高表达单倍型AG和AA频率为0.055, 低表达单倍型GG和GA频率为0.945。结果表明, 浙江汉族人群细胞因子基因多态性较为丰富, 具有地区性遗传特征。     

Two distinct poly(A) polymerases isolated from the cytoplasm of Ehrlich ascites tumour cells

The poly(A) polymerases from the cytosol and ribosomal fractions of Ehrlich ascites tumour cells are isolated and partially purified by DEAE-cellulose and phosphocellulose column chromatography. Two distinct enzymes are identified: (a) a cytosol Mn2+-dependent poly(A) polymerase (ATP:RNA adenylyltransferase) and (b) a ribosome-associated enzyme defined tentatively as ATP(UTP): RNA nucleotidyltransferase. The cytosol poly(A) polymerase is strictly Mn2+-dependent (optimum at 1 mM Mn2+) and uses only ATP as substrate, poly(A) is a better primer than ribosomal RNA. The purified enzyme is free of poly(A) hydrolase activity, but degradation of [3H]poly(A) takes place in the presence of inorganic pyrophosphate. Most likely this enzyme is of nuclear origin. The ribosomal enzyme is associated with the ribosomes but it is found also in free state in the cytosol. The purified enzyme uses both ATP and UTP as substrates. The substrate specificity varies depending on ionic conditions: the optimal enzyme activity with ATP as substrate is at 1 mM Mn2+, while that with UTP as substrate is at 10--20 mM Mg2+. The enzymes uses both ribosomal RNA and poly(A) [but not poly(U)] as primers. The purified enzyme is free of poly(A) hydrolase activity.     

根田鼠生命表和繁殖的研究

根据229((?)(?)124,♀♀105)只实验室出生的幼鼠生长、繁殖和死亡观察根田鼠雄性和雌性的期望寿命(c_0)分别为3.040(即39周)和3.176(即41周);平均死亡率((?))分别为0.283和0.272,两者很接近。妊振期平均为20.6天,哺乳期在15—20天,产仔数平均为4.56只。实验种群经一世代后的净增殖率(R_0)为2.0456,内禀增长率(r_m)为0.0787/月。     

Observation on Chromosomes of Wildflowers in China

In this paper 7 species of wildflowers were collected from Beijing suburb and Jilin Province. They are all common sightly and hardy perennials in their localities (See the Appendix for detail of the materials). The micrographs of their somatic metaphases are shown in Plate 1; the karyotype formulae, ranges of chromosome length and classification of karyotypes according to Stebbins (1971) are shown in Table 1; the idiograms of 5 species in Figs. 1-5. The karyotype analysis is made on the basis of Li and Chen (1985)⁽¹⁾. The essential points are as follows; (1) Ten pairs of chromosomes of Achyrophorus ciliatus are all submetacentric (sm). (2) Twelve pairs of chromosomes are all metacentric (m), and the short arms of the seventh pair of chromosomes with a pair of satellites in Orychophragmus violaceus. (3) The seventh and nineth pairs of chromosomes are sm and the short arms of latter with satellites in Silene repens var. angustifolia. It is reported for the first time. (4) In Scabiosa tschiliensis. the first, fourth, fifth and eighth pairs of chromosomes are sm, the sixth is terminal (t). The second and seventh are subterminal (st), the third is m. There are satellites on the short arms of third and seventh pairs. It is reported for the first time. (5) The eleventh pair of chromosomes is sm and the others are all m. The short arms of the twelfth pairs with satellites in Lychnis fulgens. (6) The chromosome number (2n) is 42, with a pair of satellites in Papaver pseudo-radicatum. It is also reported for the first time. (7) The chromosome number is2n=56 with two pairs of satellites in Rehmannia glutinosa.     

Oligopeptidase B: a new type of serine peptidase with a unique substrate-dependent temperature sensitivity

Oligopeptidase B, a member of the novel prolyl oligopeptidase family of serine peptidases, is involved in cell invasion by trypanosomes. The kinetic analysis of the reactions of oligopeptidase B, which preferentially cleaves peptides at two adjacent basic residues, has revealed significant differences from the trypsin-like serine peptidases. (i) The pH dependence of k(cat)/K(m) deviates from normal bell-shaped curves due to ionization of an enzymatic group characterized by a macroscopic pK(a) of approximately 8.3. The effect of this group is abolished at high ionic strength. (ii) The second-order acylation rate constants, k(cat)/K(m), are similar with the ester and the corresponding amide substrates, suggesting that their chemical reactivity does not prevail in the rate-limiting step. The kinetic deuterium isotope effects indicate that the rate-limiting step for k(cat)/K(m) is principally governed by conformational changes. (iii) The pH-k(cat)/K(m) profile and the very low rate constant for benzoyl-citrulline ethyl ester reveal a new kinetically influential group ionizing below the pK(a) of the active site histidine and indicate that the positive charge of arginine is essential for effective catalysis. (iv) The enzyme is inhibited by high concentrations of substrate. The mechanism of inhibition markedly varies with the reaction conditions. (v) The optimum temperature for the reactions of amide substrates is unusually low, slightly below 25 degrees C, whereas with benzoyl-arginine ethyl ester a linear Eyring plot is obtained up to 39 degrees C. The positive entropies of activation point to substantial reorganization of water molecules upon substrate binding.     

Pankovaia semitubulata gen. et sp. n. (Microsporidia: Tuzetiidae) from nymphs of mayflies Cloeon dipterum L. (Insecta: Ephemeroptera) in Western Siberia

The ultrastructure of a new microsporidian, Pankovaia semitubulata gen. et sp. n. (Microsporidia: Tuzetiidae), from the fat body of Cloeon dipterum (L.) (Ephemeroptera: Baetidae) is described. The species is monokaryotic throughout the life cycle, developing in direct contact with the host cell cytoplasm. Sporogonial plasmodium divides into 2-8 sporoblasts. Each sporoblast, then spore, is enclosed in an individual sporophorous vesicle. Fixed and stained spores of the type species P. semitubulata are 3.4 x 1.9microm in size. The polaroplast is bipartite (lamellar and vesicular). The polar filament is isofilar, possessing 6 coils in one row. The following features distinguish the genus Pankovaia from other monokaryotic genera of Tuzetiidae: (a) exospore is composed of multiple irregularly laid tubules with a lengthwise opening, referred to as "semitubules"; (b) episporontal space of sporophorous vesicle (SPV) is devoid of secretory formations; (c) SPV envelope is represented by a thin fragile membrane.     

Gravitropism in Phycomyces: threshold determination on a clinostat centrifuge

The absolute sensitivity of sporangiophores of Phycomyces blakesleeanus to centrifugal acceleration was determined on a clinostat centrifuge. The centrifuge provides centrifugal accelerations ranging from 10(-4) to 6 x g. The rotor of the centrifuge, which accommodates 96 culture vials with single sporangiophores, is clinostatted, that is, turning "head over", at slow speed (1 rev min(-1)) while it is running. The negative gravitropism of sporangiophores is characterized by two components: a polar angle, which is measured in the plane of bending, and an aiming-error angle, which indicates the deviation of the plane of bending from the vector of the centrifugal acceleration. Dose-response curves were generated for both angles with centrifugations lasting 3, 5, and 8 h. The threshold for the polar angle depends on the presence of statoliths, so-called octahedral protein crystals in the vacuoles. The albino strain C171 carAcarR (with crystals) has a threshold near 10(-2) x g while the albino strain C2 carAgeo-3 (without crystals) has a threshold of about 2 x 10(-1) x g. The threshold for the aiming error angle is ill defined and is between 10(-2) and 10(-1) x g. The threshold for the polar angle of the wild type NRRL 1555 (with crystals) is near 8 x 10(-2) x g.     

Stereochemical specificity of organophosphorus acid anhydrolase toward p-nitrophenyl analogs of soman and sarin

Organophosphorus acid anhydrolase (OPAA) catalyzes the hydrolysis of p-nitrophenyl analogs of the organophosphonate nerve agents, sarin and soman. The enzyme is stereoselective toward the chiral phosphorus center by displaying a preference for the R(P)-configuration of these analogs. OPAA also exhibits an additional preference for the stereochemical configuration at the chiral carbon center of the soman analog. The preferred configuration of the chiral carbon center is dependent upon the configuration at the phosphorus center. The enzyme displays a two- to four-fold preference for the R(P)-enantiomer of the sarin analog. The k(cat)/K(m) of the R(P)-enantiomer is 250 M(-1) s(-1), while that of the S(P)-enantiomer is 110 M(-1) s(-1). The order of preference for the stereoisomers of the soman analog is R(P)S(C) > R(P)R(C) > S(P)R(C) > S(P)S(C). The k(cat)/K(m) values are 36,300 M(-1)s(-1), 1250 M(-1) s(-1), 80 M(-1) s(-1) and 5 M(-1) s(-1), respectively. The R(P)S(C)-isomer of the soman analog is therefore preferred by a factor of 7000 over the S(P)S(C)-isomer.     

Analytic computation of the expectation of the linkage disequilibrium coefficient r2

The squared correlation coefficient r(2) (sometimes denoted Delta(2)) is a measure of linkage disequilibrium that is widely used, but computing its expectation E[r(2)] in the population has remained an intriguing open problem. The expectation E[r(2)] is often approximated by the standard linkage deviation sigma(d)(2), which is a ratio of two expectations amenable to analytic computation. In this paper, a method of computing the population-wide E[r(2)] is introduced for a model with recurrent mutation, genetic drift and recombination. The approach is algebraic and is based on the diffusion process approximation. In the limit as the population-scaled recombination rate rho approaches infinity, it is shown rigorously that the asymptotic behavior of E[r(2)] is given by 1/rho+O(rho(-2)), which, incidentally, is the same as that of sigma(d)(2). A computer software that computes E[r(2)] numerically is available upon request.     

Characterization and mapping of a new male sterility mutant of anther advanced dehiscence （t） in rice

Anther dehiscence is very important for pollen maturation and release.The mutants of anther dehiscence in rice (Oryza sativa L.) arefew,and related research remains poor.A male sterility mutant of anther dehiscence in advance,add(t),has been found in Minghui 63 and its sterility is not sensitive to thermo-photo.To learn the character of sterilization and the function of the add(t) gene,the morphological and cytological studies on the anther and pollen,the ability of the pistil being fertilized,inheritance of the mutant,and mapping of add(t)gene have been conducted.The anther size is normal but the color is white in the mutant against the natural yellow in the wild-type.The pollen is malformed,unstained,and small in the KI-I2 solution.The anther dehiscence is in advance at the bicellular pollen stage.A crossing test indicated that the grain setting ratio of the add(t) is significantly lower than that of the CMS line 2085A.The ability of the pistil being fertilized is most probably decreased by the add(t) gene.The male sterility is controlled by a single recessive gene of add(t).This gene is mapped between the markers of R02004 (InDel) and RM300 (SSR) on chromosome 2,and the genetic distance from the add(t) gene to these markers is 0.78 cM and 4.66 cM,respectively.     

Synthesis and characterization of a highly fluorescent peptidyl-phosphatidylethanolamine

The synthesis of a fluorescent lipid for use in studies of immune recognition of model membranes is described. The molecule has the basic structure HAPTEN-SPACER-LIPID, where fluorescein is the hapten, an oligopeptide (triglycine) is the spacer, and dipalmitoylphosphatidylethanolamine (DPPE) is the lipid. The spacer, which is necessary for immunological reactivity, is first linked via a peptide bond to DPPE. The free N-terminus of the peptidyl-DPPE is then reacted with 5-dichlorotriazinylaminofluorescein (DCTAF) to yield fluoresceinchlorotriazinyltriglycyl-DPPE (FG3P). The structure is confirmed by mass spectrometry and Fourier transform NMR. When FG3P is incorporated into phospholipid vesicles it retains the brilliant fluorescence and high-affinity immunological reactivity of fluorescein. The general synthesis scheme may prove useful in other membrane and lipoprotein applications.     

Kinetic and chemical mechanisms of homocitrate synthase from Thermus thermophilus

The homocitrate synthase from Thermus thermophilus (TtHCS) is a metal-activated enzyme with either Mg(2+) or Mn(2+) capable of serving as the divalent cation. The enzyme exhibits a sequential kinetic mechanism. The mechanism is steady state ordered with α-ketoglutarate (α-Kg) binding prior to acetyl-CoA (AcCoA) with Mn(2+), whereas it is steady state random with Mg(2+), suggesting a difference in the competence of the E·Mn·α-Kg·AcCoA and E·Mg·α-Kg·AcCoA complexes. The mechanism is supported by product and dead-end inhibition studies. The primary isotope effect obtained with deuterioacetylCoA (AcCoA-d(3)) in the presence of Mg(2+) is unity (value 1.0) at low concentrations of AcCoA, whereas it is 2 at high concentrations of AcCoA. Data suggest the presence of a slow conformational change induced by binding of AcCoA that accompanies deprotonation of the methyl group of AcCoA. The solvent kinetic deuterium isotope effect is also unity at low AcCoA, but is 1.7 at high AcCoA, consistent with the proposed slow conformational change. The maximum rate is pH independent with either Mg(2+) or Mn(2+) as the divalent metal ion, whereas V/K(α-Kg) (with Mn(2+)) decreases at low and high pH giving pK values of about 6.5 and 8.0. Lysine is a competitive inhibitor that binds to the active site of TtHCS, and shares some of the same binding determinants as α-Kg. Lysine binding exhibits negative cooperativity, indicating cross-talk between the two monomers of the TtHCS dimer. Data are discussed in terms of the overall mechanism of TtHCS.     

The outcome of the trade-off relation between number and viability of the offspring from the viewpoint of evolutionary stability

Life history evolution is investigated with a mathematical model. The model has 3 parameters which represent phenotypic variation among individuals of a species. The parameters are (1) clutch size, (2) viability against the (physical) environment, (3) viability against intraspecific competition. The trade-off relation between the 3 parameters is imposed. The model has one more parameter that represents the intensity of density independent mortality (harshness of the environment). The triplet of the 3 parameter values are regarded as a strategy. Analysis is made to investigate how the evolutionarily stable strategy (ESS) shifts as the intensity of the harshness of the environment increases. First, the model is analyzed in the case where variation only in (1) and (2) is allowed. The result is that the ESS shifts to be less fecund and more viable to the environment as the environment becomes harsher. Second, the case where variation only in (1) and (3) is allowed is analyzed, and the result is that the ESS shifts to be more fecund and less viable to intraspecific competition as the environment becomes harsher. Finally, the case without restrictions is analyzed and the condition for the above 2 tendencies to be expected is found. The results obtained in this paper are compared with those previously derived from the theories of life history. The general framework for the theory of life history evolution under various situations is also discussed.     

The preparation and characterization of an immobilized l-glutamic decarboxylase and its application for determination of l-glutamic acid

This paper is to study the preparation and characterization of an immobilized L-glutamic decarboxylase (GDC) and develop a sensitive method for the determination of L-glutamate using a new biosensor, which consists of an enzyme column reactor of GDC immobilized on a novel ion exchange resin (carboxymethyl-copolymer of allyl dextran and N.N'-methylene-bisacrylamide CM-CADB) and ion analyzer coupled with a CO(2) electrode. The conditions for the enzyme immobilization were optimized by the parameters: buffer composition and concentration, adsorption equilibration time, amount of enzyme, temperature, ionic strength and pH. The dynamic response of Na(2)HPO(4)-citric acid buffer system selected is much better than that of the others, 0.10 M HAc-0.10 M NaAc and 0.10 M sodium citrate-0.10 M citric acid. The initial rate of the enzyme reaction v(0) in this buffer system is 1.76 mol. l(-1) min(-1), moreover, the rate of the enzyme reaction appears linear in the first 4 min. The optimum adsorption equilibrium time is around 6 h. The amount of enzyme adsorbed on CM-CADB resin affects the response to substrate L-glutamic acid, the widest range of linearity is obtained with over 30 mg (GDC)/g(resin). The GDC activity immobilized on CM-CADB reaches a maximum when the immobilization temperature was kept around 40 degrees C. pH was kept at 4.4 when measuring the activity of the immobilized GDC. No variation of the activity of immobilized GDC is observed when the capacity is over 2.5 meq/g.(CM-CADB resin). The properties of the immobilized enzyme on CM-CADB were characterized. No significant improvement can be achieved when the substrate concentration exceeds 12.00 mmol/l, where the activity of immobilized GDC is equal to 1.58 mmol/l.min.g. The optimum pH is found to be 5.2, which changes 0.2 unit, comparing with that of the free GDC (5.0). The optimum temperature is found to be around 48 degrees C, which is lower than that of free GDC (55 degrees C). The critical temperature of the free GDC and the immobilized GDC is approximately 50 degrees C and 45 degrees C, respectively. The half-life of the activity is 127 days when the immobilized enzyme was stored in the cold (4 degrees C). An immobilized GDC enzyme column reactor matched with a flow injection system-ion analyzer coupled with CO(2) electrode-data collection system made up the original form of the apparatus of biosensor for determining of L-glutamic acid. The determination conditions are that the buffer solution is 0.10 M Na(2)HPO(4)-0.05 M citric acid at pH 4.4 and t = 37 degrees C. The limit of detection is 1.0 x 10(-)(5) M. The linearity response is in the range of 5 x 10 (-2) - 5 x 10 (-5) M. The equation of linear regression of the calibration curve is y = 43.3x + 181.6 (y is the milli-volt of electrical potential response, x is the logarithm of the concentration of the substrate of L-glutamic acid). The correlation coefficient equals 0.99. The coefficient of variation equals 2.7%.     

Phanerochaete chrysosporium beta-Glucosidases: Induction, Cellular Localization, and Physical Characterization

Phanerochaete chrysosporium produces intracellular soluble and particulate beta-glucosidases and an extracellular beta-glucosidase. The extracellular enzyme is induced by cellulose but repressed in the presence of glucose. The molecular weight of this enzyme is 90,000. The K(m) for p-nitrophenyl-beta-glucoside is 1.6 x 10 M; the K(i) for glucose, a competitive inhibitor, is 5.0 x 10 M. The K(m) for cellobiose is 5.3 x 10 M. The intracellular soluble enzyme is induced by cellobiose; this induction is prevented by cycloheximide. The presence of 300 mM glucose in the medium, however, had no effect on induction. The K(m) for p-nitrophenyl-beta-glucoside is 1.1 x 10 M. The molecular weight of this enzyme is approximately 410,000. Both enzymes have an optimal temperature of 45 degrees C and an E(act) of 9.15 kcal (ca. 3.83 x 10 J). The pH optima, however, were approximately 7.0 and 5.5 for the intracellular and extracellular enzymes, respectively.     

Theoretical study of the hypochromic effect in polynucleotides]

The first UV-absorption band hypochromicity of poly(dA)-poly(dT), poly(dG)-poly(dC), poly(dA), poly(dT), poly(dG), poly(dC), is calculated with the help of the perturbation theory. The wave functions of the bases are computed by Pariser--Parr--Pople's method taking into account all the singly excited configurations. The results obtained show a good correlation between the theoretical and experimental values of hypochromicity. A considerable influence of the vaccum electron transitions on the hypochromicity of polynucleotides is revealed. The origin of the hypochromic effect in the double-stranded polynucleotides is investigated. It is shown that intrastrand interactions between the bases make the main contribution to hypochromicity (60-76%), while the contribution of the Watson-Crick pairs is small (2-12%). The essential part of hypochromicity (22-28%) is due to the interstrand interactions between the bases which are not coupled by hydrogen bonds. The discussion of the experimental data shows that the present theoretical investigation could serve as a basis for correct treatment of experimental results.     

Bifurcation of orbits and synchrony in inferior olive neurons

Inferior olive neurons (IONs) have rich dynamics and can exhibit stable, unstable, periodic, and even chaotic trajectories. This paper presents an analysis of bifurcation of periodic orbits of an ION when its two key parameters (a, μ) are varied in a two-dimensional plane. The parameter a describes the shape of the parabolic nonlinearity in the model and μ is the extracellular stimulus. The four-dimensional ION model considered here is a cascade connection of two subsystems (S(a) and S(b)). The parameter plane (a - μ) is delineated into several subregions. The ION has distinct orbit structure and stability property in each subregion. It is shown that the subsystem S(a) or S(b) undergoes supercritical Poincare-Andronov-Hopf (PAH) bifurcation at a critical value μ(c)(a) of the extracellular stimulus and periodic orbits of the neuron are born. Based on the center manifold theory, the existence of periodic orbits in the asymptotically stable S(a), when the subsystem S(b) undergoes PAH bifurcation, is established. In such a case, both subsystems exhibit periodic orbits. Interestingly when S(b) is under PAH bifurcation and S(a) is unstable, the trajectory of S(a) exhibits periodic bursting, interrupted by periods of quiescence. The bifurcation analysis is followed by the design of (i) a linear first-order filter and (ii) a nonlinear control system for the synchronization of IONs. The first controller uses a single output of each ION, but the nonlinear control system uses two state variables for feedback. The open-loop and closed-loop responses are presented which show bifurcation of orbits and synchronization of oscillating neurons.