Effects of starvation on moult cycle and hepatopancreas of Stage I lobster(Homarus americanus) larvae

Effects of feeding and starvation on the moult cycle and on the ultrastructure of hepatopancreas cells were studied in Stage I lobster larvae (Homarus americanus Milne-Edwards). The relative significance of yolk and first food was quite different in larvae originating from two females. This difference was evident also in the amounts of stored lipid in the R-cells of the larval hepatopancreas. Most larvae from one hatch were, in principle, able to develop exclusively with yolk reserves (without food) to the second instar. The larvae from the second hatch showed lecithotrophic development only to the transition between late intermoult and early premoult (Stages C/D₀ of Drachs's moult cycle) of the first larval instar. When initial starvation in this group lasted for 3 days or more, the point of no return (PNR) was exceeded. After the PNR, consumption of food was still possible, but development ceased in the transition C/D₀ or in late premoult (D_3–4). It is suggested that these stages of the moult cycle are critical points were cessation of development and increased mortality are particularly likely in early larval lobsters under nutritional stress. Examination of hepatopancreas R-cells suggested that the PNR is caused by an irreversible loss of the ability to restore lipid reserves depleted during initial starvation. Initial periods of starvation ending before the PNR prolonged mainly Stage D₀ of the same instar (I). During this delay, structural changes in the R-cells caused by the preceding period of starvation were reversed: reduced lipid inclusions, swollen mitochondria, an increased number of residual bodies indicating autolysis, and a reduction of the microvillous processes. Continually starved larvae which showed lecithotrophic development throughout the first instar and were then re-fed after moulting successfully, had later a prolonged intermoult (Stage C) period in the second instar. This shows that, despite occasional lecithotrophy, food is an important factor in early larval development of the lobster.     

Elasnin,a new human granulocyte elastase inhibitor produced by a strain of Streptomyces

Elasnin, a new human granulocyte elastase inhibitor, has been isolated from $\text{Streptomyces}\text{noboritoensis}$ KM-2753. Elasnin is a neutral, lipophilic colorless and viscous oil ($\text{n}{}_{\mathrm{D}}{}^{17}\text{=1.4983}$, $\text{[α]}{}_{\mathrm{D}}{}^{18}\text{?0.9°}$, λ_max^EtOH 291 nm (ε, 7760)). The molecular formula was C₂₄H₄₀O₄ (M.W.: 392) as determined by its elemental analysis and mass spectrum. Elasnin inhibits markedly human granulocyte elastase, but is almost ineffective for pancreatic elastase, trypsin, chymotrypsin, thermolysin and papain.     

A stable traveling-wave solution of a model of cellular control processes with positive feedback

Edelstein's model

$\text{?E}\text{?τ}\text{=F(M, E)}$

,

$\text{?M}\text{?τ}\text{=G(M, E)+D}\text{?}{}^2\text{M}\text{?s}{}^2$

,

$\text{M(s,0)=?(s)}$

,

$\text{E(s,0)=ψ(s)}$

, where τ ? 0 and ?∞<s<∞, $\text{F(M, E>) = (K}{}_1\text{+M}{}^{\mathrm{m}}\text{)}\text{(K}{}_2\text{+M}{}^{\mathrm{m}}\text{)?k}{}_1\text{E, G(M, E)}\text{= k}{}_1\text{E ? k}{}_2\text{M,}$ m ? 2, describes the behavior of two basic chemical species during the cellular differentiation in a linear ensemble of the same cell type. We prove the existence and uniqueness of a travelling-wavefront solution. We also demonstrate one kind of stability for this solution.     

The polymorphic phase behaviour and miscibility properties of synthetic phosphatidylethanolamines

(1) The polymorphic phase behaviour of aqueous dispersions of various synthetic phosphatidylethanolamines, both singly and in mixtures, has been investigated by ³¹P-NMR. (2) $\text{14:0}\text{14:0}$ PE remains in the lamellar phase up to 90°C. $\text{18:1}{}_{\mathrm{<mtext>t</mtext>}}\text{18:1}{}_{\mathrm{<mtext>t</mtext>}}$ PE exhibits a lamellar to hexagonal (H_II) transition between 60°C and 63°C. For $\text{18:1}{}_{\mathrm{<mtext>c</mtext>}}\text{18:1}{}_{\mathrm{<mtext>c</mtext>}}$ PE, the lamellar to hexagonal (H_II) transition occurs between 7 and 12°C, whereas for $\text{18:2}{}_{\mathrm{<mtext>c</mtext>}}\text{18:2}{}_{\mathrm{<mtext>c</mtext>}}$ PE, the hexagonal (H_II) phase is the preferred structure above ?15°C. (3) Mixtures of $\text{18:1}{}_{\mathrm{<mtext>c</mtext>}}\text{18:1}{}_{\mathrm{<mtext>c</mtext>}}$ PE and $\text{18:1}{}_{\mathrm{<mtext>t</mtext>}}\text{18:1}{}_{\mathrm{<mtext>t</mtext>}}$ PE exhibit near-ideal miscibility behaviour. For mixtures of $\text{18:1}{}_{\mathrm{<mtext>c</mtext>}}\text{18:1}{}_{\mathrm{<mtext>c</mtext>}}$ PE and $\text{14:0}\text{14:0}$ PE there is evidence of fluid-solid immiscibility at temperatures below the gel-liquid crystalline transition temperature of the $\text{14:0}\text{14:0}$ PE component. Mixtures of $\text{18:2}{}_{\mathrm{<mtext>c</mtext>}}\text{18:2}{}_{\mathrm{<mtext>c</mtext>}}$ PE and $\text{18:1}{}_{\mathrm{<mtext>t</mtext>}}\text{18:1}{}_{\mathrm{<mtext>t</mtext>}}$ PE exhibit complex phase behaviour involving limited fluid-solid immiscibility at low temperatures and formation of a phase allowing isotropic motional averaging at higher temperatures. (4) ³¹P-NMR provides a graphic method for investigating the miscibility properties of mixed PE systems.     

The diffusion-concentration product of oxygen in lipid bilayers using the spin-label T1 method

A method is described to measure the oxygen diffusion-concentration product, $\text{D}{}_{\mathrm{<mtext>o</mtext>}}\text{[}\text{O}{}_2\text{]}$, at any locus that can be probed or labeled using nitroxide radicals. The method is based on the dependence of the spin-lattice relaxation time $\text{T}{}_1$ of the spin label on the bimolecular collision rate with oxygen. Strong Heisenberg exchange between spin label and oxygen contributes directly to $\text{T}{}_1$ of the spin label, while dipolar interactions are negligible. Both time-domain and continuous wave saturation methods for studying $\text{T}{}_1$ are considered. The method has been applied to phospholipid liposomes using fatty acid spin labels. A discontinuity in $\text{D}{}_{\mathrm{<mtext>o</mtext>}}\text{[}\text{O}{}_2\text{]}$ at the main phase transition was observed.     

Equilibrium constants for association of guanidinium and ammonium ions with oxyanions: The effect of changing basicity of the oxyanion

Using guanidinium and n-butylammonium cations (C⁺) as models for the positively charged side chains in arginine and lysine, we have determined the association constants with various oxyanions by potentiometric titration. For a dibasic acid, H₂A, three association complexes may exist: $\text{K}{}_{\mathrm{<mtext>1M</mtext>}}\text{=}\text{[CHA]}\text{[C}{}^{\mathrm{+}}\text{]}\text{[HA}{}^{\mathrm{?}}\text{]}$; $\text{K}{}_{\mathrm{<mtext>1D</mtext>}}\text{=}\text{[CA}{}^{\mathrm{?}}\text{]}\text{[C}{}^{\mathrm{+}}\text{]}\text{[A}{}^{\mathrm{2?}}\text{]}$; $\text{K}{}_{\mathrm{<mtext>2D</mtext>}}\text{=}\text{[C}{}_2\text{A]}\text{[C}{}^{\mathrm{+}}\text{]}\text{[CA}{}^{\mathrm{?}}\text{]}$. For guanidinium ion and phosphate, K_1M = 1.4, K_1D = 2.6, and K_2D = 5.1. The data for carboxylates indicate that the basicity of the oxyanion does not affect the association constant: acetate, pK_a = 4.8, K_1M = 0.37; formate, pK_a = 3.8, K_1M = 0.32; and chloroacetate, pK_a = 2.9, K_1M = 0.43, all with guanidinium ion. Association constants are also reported for carbonate, dimethylphosphinate, benzylphosphonate, and adenylate anions.     

Female dimorphism in honey-bee larvae with respect to glucose metabolism

The rate of conversion of glucose-1-¹⁴C and glucose-6-¹⁴C to ¹⁴CO₂ and lipid was monitored in queen and worker larvae between 48 and 96 hr of age. A definite dimorphism in glucose metabolism between castes was established. Worker larvae 72 hr of age have a much greater $\text{C}{}_6\text{C}{}_1$ ratio than do queen larvae of the same age. The ratios were of the same order of magnitude for both castes of larvae younger or older than 72 hr. Queen larvae were shown to have a greater rate of lipid synthesis than worker larvae.     

Catalytic function of thymidylate synthase is confined to S phase due to its association with replitase

Catalytic activity of thymidylate synthase, as measured $\text{in}\text{,}\text{vivo}$, is tightly linked to S phase of the cell cycle in Chinese hamster embryo fibroblast cells. This activity, as measured $\text{in}\text{,}\text{vitro}$, is found in all parts of the cell cycle. Thymidylate synthase activity in nuclear (karyoplast) extracts increased as the cells progressed from $\text{G}{}_0\text{G}{}_1$ to S phase. This enzymatic activity in the nuclei of S phase cells is associated with the multienzyme complex (replitase) that also contained DNA polymerase and other enzymes of DNA replication and precursor synthesis. The degree of association of thymidylate synthase with replitase, which increased co-ordinately as the cells progressed from $\text{G}{}_0\text{G}{}_1$ phase to S phase, coincided strongly with the level of $\text{in}\text{,}\text{vivo}$ activity of the enzyme.     

Effect of PGF2α and neostigmine on induction of parturition,farrowing interval and litter survival in swine

An investigation of the effect of PGF₂α induced parturition alone or in combination with neostigmine (NEO) on subsequent productivity was conducted in a total confinement swine production unit. Forty-five crossbred gilts and 106 sows were randomly assigned to one of six treatments: (1) $\text{0 mg PGF}{}_2\text{α}\text{0 mg NEO}$, (2) $\text{10 mg PGF}{}_2\text{α}\text{0 mg NEO}$, (3) $\text{0 mg PGF}{}_2\text{α}\text{5 mg NEO}$, (4) $\text{10 mg PGF}{}_2\text{α}\text{5 mg NEO}$, (5) $\text{0 mg PGF}{}_2\text{α}\text{10 mg NEO}$, (6) $\text{10 mg PGF}{}_2\text{α}\text{10 mg NEO}$. PGF₂α injections (IM) were given 2 days prior to the mean expected farrowing day for this farm (day 112). NEO injections (IM) were given after the fourth pig born in gilt litters and after the fifth pig born in sow litters. Females injected with 0 or 10 mg PGF₂α farrowed 71.7 ± 3.7 and 31.4 ± 3.4 hours after treatment, respectively (P<0.01). No other parameters measured were significantly affected by injection of PGF₂α. These data show that PGF₂α effectively induced parturition and did not adversely affect subsequent litter productivity. NEO was found to be ineffective in reducing total farrowing time (P>0.05).     

Preferential solvation of methylmercurated calf thymus deoxyribonucleic acid.

The changes in polymer-solvent interactions that occur when native calf thymus DNA is dialyzed against Na₂SO₄ solutions of a given ionic strength and buffer concentration but of varying concentrations in methylmercuric hydroxide have been investigated with the help of solution density measurements at 25 °C and pH 6.8–7.0. From measurements executed under equilibrium dialysis conditions at the three salt levels 5 mm, 0.05 m, and 0.5 m Na₂SO₄ (m refers to molality) and in the presence of 5 mm cacodylic acid buffer, the density increments $\text{(}\text{??}\text{?c}{}_2\text{)}{}_{\mathrm{\mu }}{}^0$ for native calf thymus DNA were determined as a function of CH₃HgOH concentration. $\text{(}\text{??}\text{?c}{}_2\text{)}{}_{\mathrm{\mu }}{}^0$ was found not to vary with organomercurial concentration, irrespective of the concentration of supporting electrolyte, until a certain CH₃HgOH concentration level has been reached, viz., , beyond which $\text{(}\text{??}\text{?c}{}_2\text{)}{}_{\mathrm{\mu }}{}^0$ increases strongly with increasing concentration of CH₃HgOH. As is shown by optical melting, $\text{(}\text{??}\text{?c}{}_2\text{)}{}_{\mathrm{\mu }}{}^0$ becomes a function of organomercurial concentration the moment DNA undergoes denaturation brought about by the complexing of CH₃HgOH with the various N-binding sites of the base residues in the DNA double helix.Polymer-solvent interactions, expressed in terms of preferential water interactions (“net hydration”) and preferential salt interactions (“salt solvation”), were derived from the $\text{(}\text{??}\text{?c}{}_2\text{)}{}_{\mathrm{\mu }}{}^0$ data in combination with data obtained on the preferential interaction of CH₃HgOH with denatured DNA and data on the partial specific volumes of all major solution components, gathered from density measurements on solutions with fixed concentrations of diffusible components. Evidence is presented which shows that denaturation in general decreases the net hydration while salt becomes preferentially associated with the polyelectrolyte. This process is further amplified by the interaction of CH₃HgOH with denatured DNA: Methylmercurated DNA alters the redistribution of diffusible components at dialysis equilibrium to such an extent that in a formal sense large amounts of water are rejected from the immediate vicinity of the polymer. The molecular implications of these findings are explored. The results are further discussed in the light of previous findings where the methylmercury-induced denaturation of DNA had been studied with the help of buoyant density measurements in a Cs₂SO₄ density gradient and by velocity-sedimentation in a variety of sulfate media.     

Control of puffing activity in three chromosomal segments of explanted salivary gland cells of Chironomus thummi by variation in extracellular Na+,K+ and Mg2+

Salivary glands of Chironomus thummi larvae were incubated in media composed of those $\text{NaCl}\text{KCl}\text{,}\text{MgCl}{}_2\text{NaCl}\text{or}\text{MgCl}{}_2\text{KCl}$ combinations and at concentrations which they tolerated without visible damage. Resulting changes in puffing activity were recorded for three chromosomal segments. Within certain combinatorial ranges $\text{NaCl}\text{KCl}\text{,}\text{MgCl}{}_2\text{NaCl}\text{and}\text{MgCl}{}_2\text{KCl}$ induced puffs in the three segments. Each inducing range is depicted as a ‘puff-inducing field’ for extracellular ion concentrations (IF^e) in a two-dimensional lattice. The IF^e_s are coherent, distinctly delineated and highly overlapping. At most places a transition from 0 to 100 % puff induction (induction of respective puff in each nucleus) depends on changes in media composition of 10–20 mM. Ion sensitivities of the three chromosomal segments were computed for NaCl/KCl/MgCl₂ combinations and were found to conform to actual puff-inducing capacities of selected NaCl/KCl/MgCl₂ media.