Correlation of phenotypes of the apterous mutation in Drosophila melanogaster

The apterous (ap) mutant in Drosophila melanogaster exhibits phenotypes of wing deficiency, precocious adult death, and nonvitellogenic oocyte development. The latter phenotype previously has been shown to result from juvenile hormone (JH) deficiency in the adult stage. To explore the relationship between the hormone deficiency and the other phenotypes, the expression of each phenotype was measured in five alleles of ap (including a new, chemically-induced allele, ap^77f) as wing length, survival five days after eclosion, and initiation and progress of vitellogenic oocyte development. No correlation could be found between severity of wing phenotype and that of precocious adult death or nonvitellogenesis. However, the latter phenotypes were correlated in both ap homozygotes and allelic heterozygotes, since adults that survive have wild-type vitellogenesis, and those fated for precocious death fail to develop vitellogenic oocytes. These results indicate that no relationship exists between wing and JH deficiencies, but that precocious adult death is related to hormone deficiency — probably through pleiotropy, rather than through causality.     

Metabolic degradation of the peptide periplanetin CC-2 in the cockroach,Periplaneta americana

We have studied the metabolism of the hyperglycemic/cardioacceleratory peptide periplanetin CC-2 (pGlu-Leu-Thr-Phe-Thr-Pro-Asn-Trp-NH₂), in Periplaneta americana using both in vitro and in vivo methods. We focused on metabolism in hemolymph, and homogenates of fat body (a presumed target organ) and Malpighian tubules (previously suggested to degrade the nonpurified cardioacceleratory factors). Despite using low concentrations (6 nM) of [4-³H-Phe]CC-2, enzymatic degradation in homogenates of fat body and Malpighian tubules proceeded with $\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ of ∼ 1 hr, while degradation in hemolymph was much slower. We injected low doses (1–2 pmol) of [³H]CC-2 into adult female cockroaches and analyzed hemolymph samples at various times; we determined the $\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$in vivo to be about 1 hr. We conclude that rate of secretion may be more important in controlling physiological levels of this peptide than rate of degradation.     

Modification of the aggregation state of the multifunctional enzyme complex catalyzing the first steps in pyrimidine biosynthesis in the course of development of Drosophila melanogaster

Mutations at the bithoraxoid (bxd) and postbithorax (pbx) loci cause a transformation of posterior haltere to posterior wing. It has previously been shown that pbx and $\text{pbx}\text{Ubx}{}^{101}$ cause this transformation by affecting the maintenance (or cell heredity function) of determination so that the transformed cells are indistinguishable from normal wing cells, and have no “memory” of having been part of a haltere disk (Adler, 1978a). I report here that Tp(3) $\text{bxd}{}^{100}\text{Ubx}{}^{101}$ and bxd¹, pbx, e^w both cause the transformation of posterior haltere to posterior wing in the same way as pbx. On the other hand, bxd¹, $\text{bxd}{}^1\text{Ubx}{}^{101}$, bxd^51j, $\text{bxd}{}^{\mathrm{<mtext>51</mtext><mtext>j</mtext>}}\text{Ubx}{}^{101}$, and $\text{bxd}{}^{\mathrm{<mtext>51</mtext><mtext>j</mtext>}}\text{red pbx}$ cause this same transformation of posterior haltere to posterior wing by interfering with the expression of the determined state so that the developmental information of posterior haltere is “misread” as posterior wing. The transformed cells in these disks retain the memory of having been part of a haltere disk; that is, these posterior cells that would secrete wing cuticle during metamorphosis regenerate anterior haltere structures. Thus it appears clear that it is possible to uncouple the expression and cell heredity functions of determination in the haltere disk of Drosophila.     

Expression of phenotypes in a temperature-sensitive allele of the apterous mutation in Drosophila melanogaster

A temperature-sensitive allele of the apterous (ap) locus of Drosophila melanogaster has been used to examine the phenotypes produced by this mutation, which include wing, mesonotal, and haltere deficiencies, precocious adult death, and nonvitellogenic oocyte development. When raised at 15°C, homozygous ap^ts78j adults have nearly wild-type wing morphology except for patches of missing triple-row bristles and posterior wing margin deficiencies. With the exception of two missing bristles, the dorsal mesonotum and the haltere appear as wild-type. Increasing deficiency of structures derived from the wing and haltere imaginal discs results from increasing culture temperature, and at 29°C, the wing blade, many dorsal mesonotal bristles, and the haltere are absent. The temperature-sensitive period in development for these deficient phenotypes extends from late-second to mid-third instar. Despite extensive deficiencies seen after ap^ts78j larvae are heat-pulsed at 29°C, no duplication of the notal structures is evident, a common response of other mutants having extensive wing deficiencies. When raised at 29 or 25°C, ap^ts78j adults are short-lived, and females show nonvitellogenic oocyte development. At 22°C, however, adults are long-lived, and females are vitellogenic and lay fertile eggs. A sharp temperature-sensitive period for both phenotypes is located during the first 24 hr of pupal development. The application of a juvenile hormone mimic, ZR-515, restored vitellogenesis to ap^ts78j females raised at 25°C but was unable to rescue them from precocious death.     

Temperature-sensitive mutations in Drosophila melanogaster. 8. Temperature-sensitive periods of the lethal and morphological phenotypes of selected combinations of notch-locus mutations

Temperature-shift experiments were performed on five Notch-locus genotypes with temperature-sensitive phenotypes. The results show that temperature-sensitive periods (TSPs) for lethality may occur at any developmental stage: (1) $\text{N}{}^{\mathrm{g11}}\text{N}{}^{\mathrm{g11}}$;Dp^51b7 having a short embryonic TSP for lethality, (2) $\text{Ax}{}^{16172}\text{N}{}^{\mathrm{?40}}$ having a second-instar TSP for lethality, and (3) $\text{N}{}^{\mathrm{?103}}\text{fa}{}^{\mathrm{no}}$ with a long, possibly polyphasic, TSP, beginning in the embryonic stage and ending in the pupal stage. On the other hand, TSPs for adult morphological phenotypes appear to be restricted to the third larval instar: (1) $\text{Ax}{}^{16172}\text{N}{}^{\mathrm{?40}}$ having third-instar TSPs for wing vein gapping and ocellar bristle loss, and (2) $\text{N}{}^{\mathrm{?103}}\text{spl}$ having third-instar TSPs for eye facet disarray, wing notching, bristle number variation, and fusion of tarsal segments. The significance of these results is discussed in terms of the role of the Notch locus in development.     

The effect of experimentally induced triploidy on the lethal expression of the t12 mutation in mouse embryos

Diploid embryos which are homozygous for the t¹² mutation die at the morula stage. In the current studies, ova from heterozygous ($\text{+}\text{t}{}^{12}$) females were fertilized in vitro with spermatozoa from $\text{+}\text{t}{}^{12}$ males. The fertilized ova were immediately placed into media containing cytochalasin B to prevent second polar body formation, producing +/+/+, +/+/t¹², +/t¹²/t¹², and t¹²/t¹²/t¹² embryos. The subsequent development of these triploid embryos was compared with that of diploid +/+, $\text{+}\text{t}{}^{12}$, and $\text{t}{}^{12}\text{t}{}^{12}$ embryos developing from ova which were also fertilized in vitro with spermatozoa from $\text{+}\text{t}{}^{12}$ males but which were not treated with cytochalasin B immediately following gamete coincubation. The data show that those triploid embryos which possess a wild-type allele and two mutant alleles are phenotypically wild type while those possessing three mutant alleles are not phenotypically distinguishable from their diploid ($\text{t}{}^{12}\text{t}{}^{12}$) counterparts. Like $\text{t}{}^{12}\text{t}{}^{12}$ embryos, t¹²/t¹²/t¹² embryos die at the morula stage, prior to blastocoelic cavity formation.     

Developmental analysis of lethal effects of homozygosity for the C25H deletion in the mouse

This report describes the phenotype of the c^25H lethal homozygote. Our studies have shown that embryos homozygous for c^25H fail to implant and to induce a decidual reaction. Embryos arrested at the three- to six-cell stage were considered to be c^25H homozygotes because of their homogeneous stage of arrest and because they were present in the appropriate proportion in preimplantation litters from $\text{c}{}^{\mathrm{ch}}\text{c}{}^{\mathrm{25H}}\text{×}\text{c}{}^{\mathrm{ch}}\text{c}{}^{\mathrm{25H}}$ matings. Mitosis appeared to be disturbed in the arrested embryos.     

Photoconversion and regeneration of active protochlorophyll(ide) in mutants defective in the regulation of chlorophyll synthesis

Seedlings carrying mutations in regulatory genes for protochlorophyll(ide) synthesis accumulate protochlorophyll(ide) in darkness in amounts exceeding the wildtype level. Thus, +/tig-d¹² and $\text{tig-b}{}^{24}\text{tig-b}{}^{24}$accumulate 2-fold, $\text{tig-o}{}^{34}\text{tig-o}{}^{34}$ 5- to 6-fold, and $\text{tig-d}{}^{12}\text{tig-d}{}^{12}$ 15-fold more protochlorophyll(ide) than the wild type.The amount of photoconvertible protochlorophyll(ide) accumulated in darkness is the same in all genotypes, despite the large differences in total protochlorophyll(ide) content, indicating a constant number of photoconversion sites.When briefly illuminated leaves are returned to darkness, regeneration of active protochlorophyll(ide) from the pool of inactive protochlorophyll(ide) takes place in wild-type and mutant leaves. Compared to the wild type, the rate of protochlorophyll(ide) activation during 4- and 10-min dark periods is higher in +/tig-d¹², $\text{tig-b}{}^{24}\text{tig-b}{}^{24}$, and $\text{tig-o}{}^{34}\text{tig-o}{}^{34}$, but lower in $\text{tig-d}{}^{12}\text{tig-d}{}^{12}$.There was no indication that the accumulation of protochlorophyll(ide) influences the conversion sites of the protochlorophyll(ide) holochrome, as the kinetics of photoconversion of initially active protochlorophyll(ide) in leaves with the genotypes +/+, +/tig-o³⁴, and $\text{tig-o}{}^{34}\text{tig-o}{}^{34}$ are similar or identical.     

A non-alkalophilic mutant of Bacillus alcalophilus lacks the Na+/H+ antiporter.

A non-alkalophilic mutant strain of $\text{Bacillus}\text{alcalophilus}$ grows on L-malate over a pH range from 5.0 to 9.0. The mutant does not exhibit the energy-dependent efflux of Na⁺ that has been used to assay a $\text{Na}{}^{\mathrm{+}}\text{H}{}^{\mathrm{+}}$ antiporter in the wild type organism. The mutant also fails to transport α-aminoisobutyric acid, at pH 9.0, either in the presence or absence of Na⁺; at pH 5.5, the amino acid analogue is taken up by a Na⁺-independent mechanism. The properties of the mutant constitute strong evidence that the $\text{Na}{}^{\mathrm{+}}\text{H}{}^{\mathrm{+}}$ antiporter is involved in maintaining an acidified cytoplasm in $\text{B}\text{.}\text{alcalophilus}$.     

Acid dissociation of cyclohexaamylose and cycloheptaamylose

Acid dissociation constants of aqueous cyclohexaamylose (6-Cy) and cycloheptaamylose (7-Cy) have been determined at 10–47 and 25–55°C, respectively, by pH potentiometry. Standard enthalpies and entropies of dissociation derived from the temperature dependences of these pK_a's are ΔH⁰ = 8.4 ± 0.3 kcal mol^?1, $\text{Δ}\text{S}{}^0\text{= ?28. ± 1}\text{cal mol}{}^{\mathrm{?1}}{}^0\text{K}{}^{\mathrm{?1}}$ for 6-Cy and ΔH⁰ = 10.0 ± 0.1 kcal mol^?1, $\text{Δ}\text{S}{}^0\text{= ?22.4 ±0.3}\text{cal mol}{}^{\mathrm{?1}}{}^0\text{K}{}^{\mathrm{?1}}$ for 7-Cy. Intrinsic ¹³C nmr resonance displacements of anionic 6- and 7-Cy were measured at 30°C in 5% D₂O ($\text{v}\text{v}$). These results indicate that the dissociation of 6- and 7-Cy involves both C2 and C3 2⁰-hydroxyl groups. The thermodynamic and nmr parameters are discussed in terms of interglucosyl hydrogen bonding.     

Nuclear magnetic resonance study of the rate of electron transfer between cytochrome c and iron hexacyanides

The rates of electron exchange between ferricytochrome c (C^III)3 and ferrocytochrome c (C^II) were observed as a function of the concentrations of ferrihexacyanide (Fe^III) and ferrohexacyanide (Fe^II) by monitoring the line widths of several proton resonances of the protein. Addition of Fe^II to C^III homogeneously increased the line widths of the two downfield paramagnetically shifted heme methyl proton resonances to a maximal value. This was interpreted as indicating the formation of a stoichiometric complex, C^III·Fe^II, in the over-all reaction:

$\text{C}{}^{\mathrm{III}}\text{+}\text{Fe}{}^{\mathrm{II}}\text{?}\text{k}{}_{\mathrm{?1}}\text{k}{}_1\text{C}{}^{\mathrm{III}}\text{·}\text{Fe}{}^{\mathrm{II}}\text{?}\text{k}{}_{\mathrm{?2}}\text{k}{}_2\text{C}{}^{\mathrm{II}}\text{·}\text{Fe}{}^{\mathrm{III}}\text{?}\text{k}{}_{\mathrm{?3}}\text{k}{}_3\text{C}{}^{\mathrm{III}}\text{+}\text{Fe}{}^{\mathrm{II}}$

Values for $\text{k}{}_1\text{k}{}_{\mathrm{?1}}\text{= 0.4 × 10}{}^3\text{m}{}^{\mathrm{?1}}\text{and}\text{k}{}_2\text{= 208}\text{s}{}^{\mathrm{?1}}$, respectively, were calculated from the maximal change in line width observed at pH 7.0 and 25 °C. Changes in the line width of C^III in the presence of Fe^II and either KCl or Fe^III suggest that complexation is principally ionic, that Fe^III and Fe^II compete for a common site. Addition of saturating concentrations of Fe^III to C^III produced only minor changes in the nuclear magnetic resonance spectrum of C^III suggesting that complexation occurs on the protein surface.Addition of Fe^III to C^II in the presence of excess Fe^II (to retain most of the protein as C^II) increased the line width of the methyl protons of ligated methionine 80. A value for k_?2 ≈ 2.08 × 10⁴ s^?1 was calculated from the dependence of linewidth on the concentration of Fe^II at 24 °C. These rates are shown to be consistent with the over-all rates of reduction and oxidation previously determined by stopped flow measurements, indicating that k₂ and k_?2 were rate limiting. From the temperature dependence the enthalpies of activation are 7.9 and 15.2 kcal/mol for k₂ and k_?2, respectively.     

Respiration-driven proton translocation with nitrite and nitrous oxide in Paracoccus denitrificans

(1) $\text{H}$⁺/electron acceptor ratios have been determined with the oxidant pulse method for cells of denitrifying Paracoccus denitrificans oxidizing endogenous substrates during reduction of O₂, NO^?₂ or N₂O. Under optimal H⁺-translocation conditions, the ratios $\text{H}{}^{\mathrm{+}}\text{O}$, $\text{H}{}^{\mathrm{+}}\text{N}{}_2\text{O}$, $\text{H}{}^{\mathrm{+}}\text{NO}{}^{\mathrm{?}}{}_2$ for reduction to N₂ and $\text{H}{}^{\mathrm{+}}\text{NO}{}^{\mathrm{?}}{}_2$ for reduction to N₂O were 6.0–6.3, 4.02, 5.79 and 3.37, respectively. (2) With ascorbate/N,N,N′,N′-tetramethyl-p-phenylenediamine as exogenous substrate, addition of NO^?₂ or N₂O to an anaerobic cell suspension resulted in rapid alkalinization of the outer bulk medium. $\text{H}{}^{\mathrm{+}}\text{N}{}_2\text{O}$, $\text{H}{}^{\mathrm{+}}\text{NO}{}^{\mathrm{?}}{}_2$ for reduction to N₂ and $\text{H}{}^{\mathrm{+}}\text{NO}{}^{\mathrm{?}}{}_2$ for reduction to N₂O were ?0.84, ?2.33 and ?1.90, respectively. (3) The $\text{H}{}^{\mathrm{+}}\text{oxidant}$ ratios, mentioned in item 2, were not altered in the presence of $\text{valinomycin}\text{K}{}^{\mathrm{+}}$ and the triphenylmethylphosphonium cation. (4) A simplified scheme of electron transport to O₂, NO^?₂ and N₂O is presented which shows a periplasmic orientation of the nitrite reductase as well as the nitrous oxide reductase. Electrons destined for NO^?₂, N₂O or O₂ pass two H⁺-translocating sites. The $\text{H}{}^{\mathrm{+}}\text{electron}$ acceptor ratios predicted by this scheme are in good agreement with the experimental values.     

Double dependence of organic acid active transport in proximal tubules of surviving frog kidney on sodium ions I. Influence of sodium ions in bath medium on the uptake and run out of fluorescein and uranin

With the aid of direct microfluorimetric determination of marker organic anions (fluorescein and uranin) accumulated in the proximal tubules the influence of Na⁺ in the bath medium on the active transport of these anions was studied. Kinetic analysis of the rate dependence of organic acid active transport into tubules on their concentration in the bath medium with a constant Na⁺ concentration permitted to define values of apparent $\text{K}{}_{\mathrm{<mtext>m</mtext>}}$ and $\text{V}$ for uranin and fluorescein transport in the medium with different Na⁺ content. It was shown that a decrease of Na⁺ concentration in the medium increases $\text{K}{}_{\mathrm{<mtext>m</mtext>}}$ and lowers the $\text{V/K}{}_{\mathrm{<mtext>m</mtext>}}$ ratio with uncharged $\text{V}$. By varying the Na⁺ concentration in the medium with a constant concentration of the marker anion the and values for fluorescein and uranin transport were determined. A value for fluorescein in twice as much that for uranin. The $\text{1/K}{}_{\mathrm{<mtext>m</mtext>}}$ value for uranin transport is a linear function of Na⁺ concentration, while for fluorescein transport it is a quadratic one. Therefore it is concluded that two Na⁺ from the medium participate in active transfer of one fluorescein anion whereas only one Na⁺ from the medium is required for active transfer of one uranin anion. The run out of fluorescein from tubules preloaded with this acid is sharply reinforced by the Na⁺ omission from the medium. Thus, active transport of organic acids in proximal tubules of frog kidney is Na⁺-dependent, and Na⁺ from the medium is likely to participate directly in formation of a transport complex. When Na⁺ is absent in the medium a carrier fulfils a facilitated diffusion only.     

A novel mutant of the lac transport system of Escherichia coli.

A new type of lactose permease mutant, called lacY^f, does not actively transport the usual substrates; but it does facilitate the entry of β-galactosides into Escherichia coli K-12. The kinetics of facilitated entry, as assayed by hydrolysis of o-nitrophenyl-β-d-galactopyranoside by intact cells are identical to those observed with wild-type permease. However, the mutant permease activity is not affected by SH reagents or the substrate analog β-d-galactosyl-1-thio-β-d-galactopyranoside which strongly inhibit wild-type activity. Furthermore, the kinetics of formation of permease in the mutant following addition of inducer and the kinetics subsequent to removal of inducer differ strikingly from those observed in wild-type strains. The results are consistent with a block in the maturation of permease in the mutant resulting in the accumulation of a large amount of permease precursor. Studies of the $\text{lacY}{}^{\mathrm{+}}\text{lacY}{}^{\mathrm{f}}$ heterogenotes provide evidence for a subunit structure for the lactose permease.     

The insect brain (Na+ + K+)-ATPase Binding of ouabain in the hawk moth, Manduca sexta

(1) A quantitative study has been made of the binding of ouabain to the ($\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$ in homogenates prepared from brain tissue of the hawk moth, Manduca sexta. The results have been compared to those obtained in bovine brain microsomes. (2) The insect brain ($\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$ will bind ouabain either in the presence of Mg²⁺ and P_i, (‘Mg²⁺, P_i’ conditions) or in the presence of Na⁺, Mg²⁺, and an adenine nucleotide (‘nucleotide’ conditions) as is the case for the bovine brain ($\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$. The binding conditions did not alter the total number of receptor sites measured at high ouabain concentrations in either tissue. (3) Potassium ion decreases the affinity (increases the $\text{K}{}_{\mathrm{<mtext>D</mtext>}}$) of ouabain to the M. sexta brain ($\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$ under both binding conditions. However, ouabain binding is more sensitive to K⁺ inhibition under the nucleotide conditions. In bovine brain ouabain binding is equally sensitive to K⁺ inhibition under the both conditions. (4) The enzyme-ouabain complex has a rate of dissociation that is 10-fold faster in the M. sexta preparation than in the bovine brain preparation. Because of this, the M. sexta ($\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$ has a higher $\text{K}{}_{\mathrm{<mtext>D</mtext>}}$ for ouabain binding and is less sensitive to inhibition by ouabain than the bovine brain enzyme. (5) This data supports the hypothesis that two different conformational states of the M. sexta ($\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$ can bind ouabain.     

Induction of passive monovalent cation-exchange activity in heart mitochondria by depletion of endogenous divalent cations

Depletion of mitochondrial divalent cations by addition of the ionophore A23187 results in a marked increase in passive ${}^{42}\text{K}{}^{\mathrm{+}}\text{K}{}^{\mathrm{+}}$ exchange activity. The exchange is activated by increasing pH and temperature and inhibited by added divalent cations. The reaction is independent of the amount of A23187 present, but depends on the concentration of external K⁺ (K_m = 25 mm). Intramitochondrial ⁴²K⁺ in cation-depleted mitochondria exchanges passively with external Na⁺ and Li⁺, but not with choline⁺. The evidence suggests that removal of mitochondrial divalent cations by A23187 activates the endogenous $\text{K}{}^{\mathrm{+}}\text{H}{}^{\mathrm{+}}$ exchange component of the mitochondrion and that the activated exchanger promotes cation/cation exchange in the absence of a metabolic pH gradient.     

Index measures for assessing the mode of inheritance of continuously distributed traits: I, theory and justifications

A class of indices that may be applied to quantitative data on nuclear families and that can help to assess degrees of mode of inheritance is developed. Given phenotype values of spouses x⁽¹⁾ and x⁽²⁾ and offspring y, the deviation of an offspring value from the midparent is $\text{¦y ?}\text{1}\text{2}\text{(x}{}^{\mathrm{(1)}}\text{+ x}{}^{\mathrm{(2)}}\text{)¦}$, and those from the separate parents are $\text{¦y ? x}{}^{\mathrm{(1)}}\text{¦}$ and $\text{¦y ? x}{}^{\mathrm{(2)}}\text{¦}$. The indices called major-gene indices (MGI) investigated are functions of the deviations from midparental values compared to corresponding symmetric functions of the deviations from separate parents. Major-gene indices exceeding 1 may indicate some extent of major-gene inheritance, whereas an MGI less than 1 is suggestive of relatively more polygenic inheritance. Superposition of assortative mating and environmental effects will tend not to shift the MGI greater than 1 for polygenic inheritance, nor will they shift the MGI less than 1 for major-gene factors. The reliance on the proposed indices is reinforced on the basis of a hierarchy of representative models of monogenic and multifactorial inheritance. Extensions of the method to deal with multigenerational pedigrees are briefly discussed.     

Tyrosine metabolism for cuticle tanning in the tobacco hornworm, Manduca sexta (L.) and other Lepidoptera: identification of beta-D-glucopyranosyl-O-L-tyrosine and other metabolites

When [${}^{14}\text{C}$]tyrosine and [${}^{14}\text{C}$]glucose were fed or injected into feeding fifth-instar larvae of the tobacco hornworm, Manduca sexta (L.), they were incorporated into a conjugate identified in hemolymph and carcass extracts as β-d-glucopyranosyl-O-l-tyrosine. In wandering larvae and pupae, the conjugate was hydrolyzed, and tyrosine was hydroxylated and decarboxylated to dihydroxyphenylalanine and 2-(dihydroxyphenyl)ethylamine. None of these metabolites were formed in fourth-instar larvae or in adults. [${}^{14}\text{C}$]Phenylalanine was hydroxylated to tyrosine in all stages of insect development. β-d-Glucopyranosyl-O-l-tyrosine was also detected in 18 other species of Lepidoptera but not in species from other insect orders. This conjugate appears to be the major tyrosine storage metabolite for production of tanning diphenol substrates in Lepidoptera.     

Fluid transport in Calliphora Malpighian tubules: A diuretic hormone from the thoracic ganglion and abdominal nerves

The rate of fluid secretion in vitro by Malpighian tubules of 3-day-old adult blowflies (Calliphora vicina) is increased by more than 8 times when exposed to an extract of the fly's thoracic ganglion and abdominal nerves. Smaller amounts of stimulatory activity are also retrievable from other body tissues: some activity is present in the brain, but other tissue activity is consistent with the presence of the stimulatory factor in fine branches of the abdominal nerves. It is suggested that this factor is a diuretic hormone.Maximal stimulation of fluid secretion is achieved within 2–3 min of exposure to the hormone, but the rate of secretion decays only slowly when the hormone is removed ($\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{=}\text{approx. 35 min}$).The hormone is stable to boiling and freezing, and enzyme experiments suggest it is a polypeptide.The hormone is inactivated when incubated in the presence of haemolymph, but the Malpighian tubules themselves do not appear to break down or excrete the hormone.     

A simple procedure for resolution of Escherichia coli RNA polymerase holoenzyme from core polymerase.

The association constant, K_A, for myosin subfragment-1 binding to actin was measured as a function of ionic strength [KCl, LiCl, and tetramethylammonium chloride (TMAC)]and temperature by the method of time-resolved fluorescence depolarization. The following thermodynamic values were obtained from solutions of 0.20 × 10^?6m S-1, 1.00 × 10^?6m actin in 0.15 m KCl, pH 7.0, at 25 °C: ΔG ° = ?39 ± 1 kJ M^?1, ΔH⁰ = 44 ± 2 kJ M^?1 and $\text{ΔS}{}^0\text{= 0.28 ± 0.01 kJ}\text{M}{}^{\mathrm{?1}}{}^0\text{K}{}^{\mathrm{?1}}$. For measurements in KCl (0.05 to 0.60 m), In $\text{K}{}_{\mathrm{a}}\text{= ?8.36 (KCl)}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$. Thus, the binding is endothermic and strongly inhibited by high ionic strength. When KCl was replaced by LiCl or TMAC the ionic effects on the binding were cation specific. The nature of actin-(S-1) binding in the rigor state is discussed in terms of these results.